Yes, the heating can sometimes cause this with some vial caps... basically it gets hot enough to develop a new form memory and stayed there long after the pressure had subsided.. Only had it happen maybe 3 times in 10 years though.Has this happened to any of u before?
Definitely an effect of the melt/re-hardening then. Sucks but at least it is just one partial vial.However i just discarded it because when I draw test it just leaks through the holes in the cap.