Yeah, sometimes mail gets stuck in the sorting machines and gets torn, or a box will get slightly crushed, etc. They will usually put a sticker on it, or if the mail was opened in the incident they will put it in a new bag with a sticker on it and send it on the way. I've even gotten spam mail (like fliers and stuff) with the notification that it was damaged by machines. I would think that you could still place a claim with USPS if the package was sent priority.