Most sniping programs bid within the last 10 seconds (some 3 seconds before auction end). If your bid was $13.93 and the sniper bid was $13.51, your bid would still win even though it wasn't a full dollar increment above theirs. You can win even by a penny, for example if their bid was $13.92.
I haven't paid a lot of attention, but I thought lately that a lot of auctions are "private" in that they do not display all the bids. Maybe this is one of those?
If you post the auction number, we can look at the actual listing.