See McNulty, 804 A.2d at 1263. Whether a disability results from an "aggravation" of a pre-existing condition or a "recurrence" of a prior injury is a question of fact to be determined by the WCJ. See Reliable Foods, Inc. v. W.C.A.B. (Horrocks), 660 A.2d 162, 166 (Pa. Cmwlth. 1995). Section 416 of the Workers' Compensation Act ("the Act")