I checked the back end, and everything looks right. You won that match, and you've got the right number of wins and losses, too. However, the match immediately before that one was a loss. It was a loss by connection error, which means that the duel had an error and our computer judged that it was either your connection or your web browser that caused it. You were up against a level 1, too. You must have given him a ton of experience points and RP.
"Scissors are overpowered. Rock is fine." -Paper