Just won a 4 player game and lost skill?

I just won a 4 player all vs all game and lost 4 skill points? How is this possible? The players I played were all below me in skill but seriously WTF

[Darkblades]

Yep..it's a bug.
For the others, theres the link of the game http://www.creeptd.com/en/games/zzt0z2l ... d2nsgkjzxw