It must have been a disconnection somewhere, cause the game was declared undecided by the server. No team was sufficiently enough ahead to be declared a winner. You can see the game progress here:
The game might have told you that you were the winner, but that is because it has no chance of knowing what happened to the other players. The other players also thought they were the winners, so the game was invalid. In these situations the server looks at the game to see if there was a clear leader, but there wasn't in this case so it just invalidated the game.