That will be interesting to hear about. One way to cross-check the bolt face is to decap a fired case and draw it gently over a piece of sandpaper that is sitting on something flat, like a bit of scrap plate glass, to see if it marks the brass high in the center or all on one side. A full pressure load usually forms the head to its surface, insofar as far as it can.
Note that a standard headspace gauge would perch close to the perimeter of the bolt face, so a concave bolt face could, in effect, have excessive headspace at the center but not at the perimeter so the reading could still be good.
Changing the firing pin spring may have no bearing on your main symptom, but both Bart B. and Hummer 70, both of whom have been U.S. Palma team shooters (and Hummer 70 is a twice past U.S. Palma champion), recommend changing mainsprings every half dozen years or so to eliminate weakening from taking a set. This improves ignition consistency and makes lock time shorter and barrel time more consistent. In turn, the latter factor makes it easier for the gun to keep a sweet spot load performing consistently. So if you have the bolt apart anyway, it's a cheap thing to do easily. Also, there is some evidence that cryo-treated springs don't take as much of a set as an untreated spring, if you want to try that route.
and delighted.