I had a P95DC where the slide slowly turned plum colored over several years, so it is NOT something that is usually readily apparently when factory new for the Q/C people to find.
My P95DC slide started out black, looked exactly like any other. After about four or five years, and quite a few rounds down the pipe, I thought I noticed it changing color. It was subtle at first, I thought my eyes or mind might be playing trick on me.
Over the course of the next four or five years, it slowly turned a distinct and obvious plum color.