Tom S:
I believe you are correct about the warranty not covering wear and tear on the pistol. I addition, it seems the problem that many run into is the "original owner" part. It seems when S&W doesn't want to work on a pistol, they fall back on that provision. In fact, the OP in this thread is not the original owner of the pistol.
Between 2007 and 2008, at the height of 3rd Gen buying craze, I called S&W Customer Service a couple of times (a 6904 and a 4576 frame decocker) to request a "call tag" to send in a 3rd Gen for work. They didn't ask, and I did not tell them I wasn't the original owner of the pistol. However, I always started the call by saying something along the lines of, "I'm having this problem with my pistol that I've never notice in all the time I've owned it." I would then describe the problem and then say, "Can you guys help me? I've always loved Smiths and I really like 3rd Gen autos." By the way, all those statements were true.
Now this was back in 07 and 08 when the factory had a lot of parts and there were still a fair number of guys there who were pretty familiar with 3rd Gen pistols. In fact, since the "techs" would frequently answer the CS phones when I called in to order extra parts (side plates, recoil spring guides, trigger play springs, rivets, various springs, levers, etc.), I would often get some great tips for working on my pistols.
IIRC a few years back a member of this forum who was the original owner of a 3rd Gen that could not be repaired by S&W was offered a new pistol, I thing it was an M&P. But that was then and this is now. So, who knows.
Just my $ .02