Won a game and got blacklisted. Still got the game.

It is no longer permitted by staff to get reroll's if you blacklist someone who won your GA. It's in a thread somewhere here on the forum. Either he needed to give it to you, or just take the "Not received" hit on his profile.

There are also people who blacklist all their winners, so it could also be that.
Most of the time I thank the person after receiving the game and so far I haven't got blacklisted for that

Your ratio is a bit off balance which may have led to the ga creator blacklisting you after you won. It is not so much as you did anything wrong, but more of giving other peeps a better shot in future giveaways.