its pretty funny you bring this up, I just sold and shipped a bunch of car parts the last 2 weeks ago and had the exact same thing happen with one of my packages. The guy who bought it was going ballistic saying I scammed him and never shipped anything blah blah blah. I goto my post office to check, they dont have it and say to have him check with his local office... turns out his post office never scanned it in and it had been sitting in his local post office in montana for 8 days on a shelf. So you might want to have him swing by his post office and check if it is just sitting there.... if it is hopefully they are honest enough to repay you