Hold on now. If you say this happened WHILE heat treating, then those aint frets. Especially if you forced the bow into reflex while doing the treating. They are tension cracks from over stressing the belly while heat treating and putting the bow into a reflex. If you dont feel any raised wood there, those are not chrysels. Just fill with super glue best as you can, scrape the limbs until you can brace it, tiller to your desired draw weight, and shoot. I think you will be ok.