I don't mean to be a SA but good luck getting brass to wear out case-hardened steel. That's part of the point of using brass. Brass is significantly softer than steel. IMO, you couldn't live long enough to chamber enough rounds (by hand) to ever wear the chamber by a measurable amount if you tried 24x7x365 for the rest of your life.

The chip appears to be a manufacturing defect to me or may have just happened but it is not "wear" per se. I'd shoot the heck out of it and never worry about it if it were me.

S&W will probably replace it but only from a liability standpoint because you have now raised the issue. They will err on the side of caution (read: the lawyers said replace it) but probably not because it matters.