Smoking Epoxy

Just used some flex coat slow cure on a grip. Next mixed a batch for the reel seat after I rolled on some tape bushings. Same procedure each time (warmed bottles with warm tap water), same bottles of epoxy. The epoxy I mixed for the reel seat began to harden after about 7 minutes. Once it started to harden it was solid in about 2 minutes and while it was hardeneing before my eyes started to give off a white smoke. The reel seat turned as I aligned it with the spine of the rod and acted normally even when the epoxy in the cup had completely hardened. Anyone ever had this happen or know why it happened?
Thanks,
Joe