found the answer =P

Do you have an RC asking for a dust jacket? If not than I don't see why you would be so mad about it not havign one that you wouldn't inspect the book.  DJ's aren't required.  If you had an RC requiring one then you should have marked it RWP and asked for your credit back for that. 

I don't normally do anything if I find damage to a book a while after marking it received.  You could try PMing them and asking for a credit refund. But personally if someone PM'd me months after receiving a book and told me it was damaged, I would wonder if it got damaged at their house and not refund the credit.