I would probably help him with his settings and see if there is maybe something he has set wrong.
Looking at your listing, you don't really have anything in there stating a seller policy concerning your items. It may benefit you in the future to have something stating what your terms are for items you sell used.
I personally would think that since he tested it and said it was okay already you would be in the clear, but, what I think versus what paypal may think are two different things.