Concurring Opinion by
Judge Doyle:Although I agree with much of the rationale set forth by the majority, I cannot embrace the reasoning in its entirety. I think that the meaning of Section 1125.1 is a question we need not reach because I believe that the doctrine of equitable estoppel applies to this case and operates to bar the School District from reducing Mr. Cucinellis seniority by more than fifteen days. While it is true that a mutual mistake as to law is not a basis for invoking this doctrine, Gabovitz v. State Automobile Insurance Association, 362 Pa. Superior Ct. 17, 523 A.2d 403 (1987), the “mistake” here was, in my view, neither mutual nor legal. The July 1982 letter in no way suggests that it constitutes a legal opinion. To the contrary, it reads as a discretionary administrative decision. Further, because the letter does not express a legal opinion, Mr. Cucinelli, a fortiori, could not have “mutually” embraced a mistaken legal opinion. Thus, I would hold that equitable estoppel alone bars the school district from reducing Mr. Cucinellis seniority by more than fifteen days. Additionally, I must add that while it is true that Wilchenski v. Throop Borough School District, 383 Pa. 394, 119 A.2d 510 (1956) did not expressly say the hiatus at issue there constituted a break in service, Judge Mencer, in Andresky v. West Allegheny School District, 63 Pa. Commonwealth Ct. 222, 437 A.2d 1075 (1981), stated, “In Wilchenski, the Court ruled that a teachers absences constituted a break in *352service for seniority purposes where the teacher was absent from work for approximately two months because of physical complications arising during pregnancy and no formal or express leave had been authorized by the school board!’ Id. at 228, 437 A.2d at 1079 (emphasis added in part).