It's possible you already had the new improved striker/firing pin which was beefed up, pictures of the new style striker/firing pin are on SigTalk forum. They also reamed the striker/firing pin hole in the slide to accommodate the new striker/firing pin. Seems they are working out the problems but what is odd is that many of the early guns like LBmN seem to be OK. But if he send his in for some problem they will update it.Smart move. They listed replacing the extractor and extractor assembly, but they also replaced the barrel even though they did not list it. Barrel was ok, as far as I could tell, and had no problems feeding, so this is curious.
I have a feeling the firing pin was replaced as well, but that's just a feeling I have with nothing to go on than it looks different.
I'll let you know how it goes today and this weekend, when I plan on putting at least a couple of hundred rounds through. Not a torture test, by any means, just a full day of running it. No repeated mag dump after dump, because personally I think that's not accomplishing anything.
I'll let you know by pm or maybe a short post.