I received a book yesterday that had obviously gotten caught in one of the USPS sorters. Half of the back cover is black and rippled (like a rubber wheel kept rubbing on it) and several pages are ripped. Then I received an email that a book that I had mailed, had arrived in the same condition. I did mark the book damaged by USPS and did NOT ask for my credit back as it was not the senders fault but now I am out money as this wish list  book does not meet swapping conditions.

I have never had this happen and was wondering if I should say something to the clerks at my PO. The only common element is both of these books went thru   Warrendale.

anyone have any words of wisdom for me? :)

I've received books in that condition as well. Unless it's insured, the USPS will likely apologize but there's no recourse AFAIK. The one thing I did notice is that the vast majority of the time that I received books in that condition the book was shipped loose in an envelope or bubble mailer that was way too big for the book. It looked like a corner of the envelope got caught in machinery and it wore down until it finally hit the book. I make sure my books are firm inside the packaging and cannot move around within and AFAIK have never had one arrive damaged.

Yeah, I don't think there is any recourse to be had. I also second the note about wrappers being tight. That's the best protection for the book. I had had a hardcover arrive once, where if you had put it upright on a bookshelf, the whole book was bent into a C shape. Have no idea how the post office did it, and I'm not sure it was even unpostable,  but the PO works in mysterious ways.

Warrendale is rather infamous for lost and damaged books/media mail.  Unfortunately, not much recourse over damaged books.

I would show the book to your local postmaster, and then tell him/her that you also mailed one out that was received in a similar condition. Perhaps they can do a report and track down the faulty equipment or find out where the mail is being mishandled. You can't be the only person in the area that is having a problem, if it's happened more than once. The problem with stuff like this sometimes is that people will fail to report problems and just brush them off.  If enough people report a problem, maybe they can pinpoint where the issue is happening.