At 1:00 A.M. on November 7, 1979, defendant Viegas arrived at Logan Airport in Boston from Florida with no apparent cloud over him. Later that day his suitcase, which he was required to leave behind, was opened and found to contain 290 grams of cocaine, for the possession of which he now stands convicted. Our question, procedurally presented by two appeals, is whether the court erred in denying (without findings, United States v. Payton, 1 Cir., 1980, 615 F.2d 922) his motion to suppress.
The evidence warranted the following. At midnight two special agents of the Drug Enforcement Administration had observed one Brooks inquire at the Delta Airlines ticket counter where bags from Flight 488 from Miami would appear. Miami is a recognized cocaine source. After being directed to the carousels on the lower level he drove his car from the upper level and parked by the lower level and returned to the lounge. Later Brooks proceeded to the appropriate gate and appeared to place a phone call. While talking he kept the booth door open and “was looking up and down the concourse.” Later he stood where deplaning passengers would pass, and when defendant arrived met, but did not shake hands with him. Both men then entered adjoining phone booths. Although it later developed that Brooks placed a collect call to his residence, the agents testified that neither man put any coins in the phones.1 Both kept their doors open and were “peering out of the phone booths, looking up and down the corridor in each direction” and appeared to be talking to each other. An agent testified that this action was “consistent with activity that is displayed by drug couriers ... to identify surveillance.”
Brooks’ original behavior directed the agents’ attention to Viegas, and the combined activity excited their suspicions sufficiently for them to follow them down to the carousel. On this trip Brooks and defendant, alternately, turned and looked behind them five or six times. While waiting for the luggage they, again, “were constantly looking around.”
When Viegas obtained his bag, both started towards the parking lot. The agents joined them as they walked, one saying to defendant, essentially, “Pardon me, sir, I am a federal narcotics agent, and I’d like to talk to you a moment,” and displayed a badge. The agents denied that they used the word “stop,” but conceded they expected the men to stop. The men did stop. Without voicing any objection, defendant answered where he had come from; why he had gone there (to visit a girl friend); proffered his ticket stub, and when asked for identification, handed over his driver’s license. All were consistent.
The agent then asked Viegas if he had drugs in his bag, and he replied in the negative. During this exchange perspiration appeared on his brow, although it was a cold night; he paled and his hand shook. An agent told Viegas that the DEA had received a call from Miami regarding someone seen there matching his description and valise. This was untrue.2 Asked if he *44would open his bag, but told that he need not, defendant refused. Asked if he would permit a detector dog sniff, he said, “Okay, get your dog.” Defendant was then asked if he would go to the office, and he said, “Yes.” When it developed that no dog was available, he was told he was free to leave, but that the bag would be detained. He departed, leaving his bag, for which a warrant was subsequently obtained.
We are presented with two factual questions: whether defendant was “seized,” viz., was, at any point, not free to leave, which would put a different character of the voluntariness of his behavior, and whether, if he was seized, the agents had reasonable grounds for suspicion, which would put their conduct in the clear in any event. Both parties recognize that the test, in each instance, is how the objective facts would appear to a reasonable person, e. g., United States v. Mendenhall, 1980, 446 U.S. 554, 100 S.Ct. 1870, 1876, 64 L.Ed.2d 497 (opinion of Stewart, J.), 100 S.Ct. at 1875, n.3 (White, J., dissenting); United States v. Wylie, D.C.Cir., 1977, 569 F.2d 62, cert. denied, 435 U.S. 944, 98 S.Ct. 1527, 55 L.Ed.2d 542, but devote much of their briefs to subjective argument. Thus defendant claims that seizure is established if the agents’ actual reason for questioning him was suspicion of criminal activity. This is incorrect. United States v. Vargas, 1 Cir., 1980, 633 F.2d 891 n.10. Alternatively, the government claims it is disproved if the agents’ intent, though unexpressed, was at all times to allow defendant to leave whenever he wished. This, too, is incorrect. Absent any direct evidence, the question is what should defendant, objectively speaking, reasonably have believed.
A “seizure” of the person has occurred, and Fourth Amendment rights arise, when “the officer, by means of physical force or show of authority, has in some way restrained the liberty of a citizen” such that he is not free to walk away. Terry v. Ohio, 1968, 392 U.S. 1, 16, 19 n.16, 88 S.Ct. 1868, 1878, n.16, 20 L.Ed.2d 889. This determination is not always an easy one, and particularly in the context of a polite stop by an investigative officer the question may be “extremely close.” United States v. Mendenhall, ante, 100 S.Ct. at 1880 n.1 (Powell, J., concurring); see United States v. Wylie, ante, 569 F.2d at 73 (Robinson, J., dissenting in part). Where there is acquiescence to an officer who has flashed his badge and requested an interview, there may be subtle questions concerning the individual’s capacity to understand his rights and even his desire to avoid incurring wrath or further suspicion. “Many people at bottom will think twice before spurning an importuning policeman.” United States v. Wylie, ante, 569 F.2d at 73 (Robinson, J., dissenting in part). On the other hand, we think the district court’s view, that there is no difference between being asked to stop, and the posing of a question which the agent believes may result in a stop, is over-simplistic. A person merely asked for directions may well be expected to stop, but he would hardly regard it as a seizure.
We need not determine, however, whether, or when,3 defendant’s person was seized, for even assuming this to have occurred at the initial contact, we think the agents’ conduct satisfied the Fourth Amendment’s test of reasonableness. See United States v. Brignoni-Ponce, 1975, 422 U.S. 873, 878, 95 S.Ct. 2574, 2578, 45 L.Ed.2d 607. Whether a particular police action is reasonable “is judged by balancing its intrusion on the individual’s Fourth Amendment interests against its promotion of legitimate governmental interests.” Delaware v. Prouse, 1979, 440 U.S. 648, 654, 99 S.Ct. 1391, 1396, 59 L.Ed.2d 660 and cases cited. This latter, in turn, depends upon the officer’s ability “to point to specific and articulable facts which, taken together with *45rational inferences from those facts, reasonably warrant that intrusion.” Terry, ante, 392 U.S. at 21, 88 S.Ct. at 1879. In determining which inferences are rational, due credit must be given to the experience and expertise of the officers. Mendenhall, ante, 100 S.Ct. at 1882 (Powell, J., concurring); Brown v. Texas, 1969, 443 U.S. 47, 52 n.2, 99 S.Ct. 2637, 2641, n.2, 61 L.Ed.2d 357; Brignoni-Ponce, ante, 422 U.S. at 885, 95 S.Ct. at 2582.
The facts before the agents, viewed in their entirety,4 adequately justified the initial inquiry. There was no extended detention, no indication that defendant was in a particular hurry, and no search of his person or (initially) of his belongings. The slight intrusion of this encounter was supported by the pair’s evasive actions in the airport, viewed in the light of defendant’s arrival from a known distribution center. It is no answer to say, as does defendant, that his actions were “consistent with innocent behavior.” See United States v. McCaleb, 6 Cir., 1977, 552 F.2d 717, 720. “It must be rare indeed that an officer observes behavior consistent only with guilt and incapable of innocent interpretation.” United States v. Price, 2 Cir., 1979, 599 F.2d 494, 502; see Terry, ante, 392 U.S. at 22, 23, 88 S.Ct. at 1880. We are concerned only with reasonable, articulable grounds for suspicion, and the district court was warranted in finding them present here.5
Defendant next challenges the detention of his suitcase, declaring it a “warrantless seizure [which] must be justified by an exception to the fourth amendment’s warrant requirement.” All agree that for the agents to open the suitcase required probable cause and, absent an exception, a warrant. The same rule does not apply, however, to a temporary detention pending investigation. United States v. VanLeeuwen, 1970, 397 U.S. 249, 90 S.Ct. 1029, 25 L.Ed.2d 282; United States v. Klein, 7 Cir., 1980, 626 F.2d 22, 25-26. Although defendant was doubtless inconvenienced by the detention of his luggage (though less so than if he were going away rather than returning home), the impact on his reasonable expectation of privacy, Katz v. United States, 1967, 389 U.S. 347, 361, 88 S.Ct. 507, 516, 19 L.Ed.2d 576 (Harlan, J., concurring), in no way compares with an actual search of the contents. United States v. Chadwick, 1977, 433 U.S. 1, 13 & n.8, 97 S.Ct. 2746, 2484, n.8, 53 L.Ed.2d 538. Rather than probable cause, such a detention is governed by the same standard as a temporary detention of the person, i. e., reasonable suspicion. The various behavior information already before the agents satisfied this test.
Defendant’s final complaint is that the warrant to search his luggage was not supported by probable cause. The affidavit in support recited the above facts, and some others. Defendant, although told he could call for his valise, had not done so.6 More significantly, a check of the files revealed that a confidential informant had told the DEA that defendant had been dealing in cocaine; that in 1978 the informant had observed defendant with large quantities of same and had purchased some from him; and that defendant brought the cocaine in from Florida. Other information from the same source had been independently corroborated in the past.7 We hold that the affi*46davit met the two-pronged test of Spinelli v. United States, 1969, 393 U.S. 410, 89 S.Ct. 584, 21 L.Ed.2d 637. First, the source was apparently reliable. Second, the information was based on the personal observations of the informant, as duly recited in the affidavit. Defendant argues that these observations, being a year old, were “stale,” insufficient “to justify a finding of probable cause at that time.” Sgro v. United States, 1932, 287 U.S. 206, 210, 53 S.Ct. 138, 140, 77 L.Ed. 260 (emphasis added). He forgets that although “a warrant’s validity depends in part on ‘the proximity or remoteness of the events observed,’ nevertheless the determination of timeliness as an element in probable cause must be by the circumstances of each case.” United States v. DiMuro, 1 Cir., 1976, 540 F.2d 503, 516, cert. denied, 429 U.S. 1038, 97 S.Ct. 733, 50 L.Ed.2d 749; see United States v. Dauphinee, 1 Cir., 1976, 538 F.2d 1, 5. Obviously, the year-old observation did not, by itself, establish probable cause that defendant was carrying cocaine in the airport. If its probative value was slight, however, its corroborative value was more significant. In this regard it is crucial that the agents received this information only after their contact with defendant; their initial observations and deductions were not influenced by it. The cumulative effect was to establish probable cause to search defendant’s bag.
This case presents the common picture of “a proper progression of escalating responses to circumstances which generated a mounting degree of suspicion.” United States v. Wylie, ante, 569 F.2d at 66; see Terry, ante, 392 U.S. at 10, 88 S.Ct. at 1874. We hold the court warranted in denying defendant’s motion to suppress.
Affirmed.
. It may be said for the agents that their observation was not blatantly faulted by the record evidence that Brooks did make a call, since that call was collect. They might easily overlook the single coin initially inserted to reach the operator. Viegas did not testify. There is no evidence that he made any call.
. This may be thought to diminish, but it could not eliminate (since defendant knew he carried no valise, having checked it through from an*44other point), the significance of his anxious demeanor during questioning.
. The bases for suspicion, and hence for detaining defendant’s suitcase, were all obtained pri- or to the retaining of his license during the walk to the office, a possible watershed point in the seizure question. Cf. Dunaway v. New York, 1979, 442 U.S. 200, 99 S.Ct. 2248, 60 L.Ed.2d 824.
. The dissent “consider[s] each factor in turn.” We may agree that some were of little consequence. However, a picture may be composed of “a series of acts, each of them perhaps innocent in itself, but which when taken together warranted further investigation.” Terry v. Ohio, ante, 392 U.S. at 22, 88 S.Ct. at 1880.
. There was considerably greater cause for suspicion here than in Reid v. Georgia, — U.S. —, 100 S.Ct. 2752, 65 L.Ed.2d 890 (1980). In particular, defendant’s and Brooks’ frequent glances over their shoulders at no one in particular (Reid was looking at a man who had exited the same plane and later joined him), and their actions in the telephone booths, would reasonably suggest attempted detection, and evasion, of surveillance.
. How suspicious that was, however, depends on what time the affidavit was made out, which did not appear.
. We are inclined to discount the affidavit’s further recital that a police detective had reported in 1978 that defendant was planning to transport cocaine from Florida to Massachu*46setts. Although credit must be given for the source, we assume that this was not first hand information. The affidavit gives no details, and none of the underlying circumstances, from which the officer reached this conclusion. See Spinelli v. United States, 1969, 393 U.S. 410, 416, 89 S.Ct. 584, 589, 21 L.Ed.2d 637; Aguilar v. Texas, 1964, 378 U.S. 108, 113, 84 S.Ct. 1509, 1513, 12 L.Ed.2d 723. But see United States v. Harris, 1971, 403 U.S. 573, 580-83, 91 S.Ct. 2075, 2080, 29 L.Ed.2d 723 (plurality opinion of Burger, C. J.)