Hey Todd99,
Yes, I believe they are heat pressed. Had the same issue when I installed my headers. I had my Porsche mechanic take care of it for me. Anyway, he did heat them up as you did/will. He then replaced them with OEM hardware (re: M8 nut; M8 x 20 mm bolt for an automatic transmission and M8 x 60mm bolt for a manual transmission).
Good luck. Let us know how it goes.