Before you make your first move, you have the option to abort your game at no cost. For example if you don't have time to play. I think ,though I may be wrong, that if your opponent presses this then it comes up as the server aborting it. Also, if you click on the same seek simultaneously with someone else, then one player might be registered as playing 2 games at once and so the server will just abort them both.
In short, it's nothing to worry about - you just have to put up with it I'm afraid!
On a number of occasions when I've started an online game, a message comes up saying the game has been aborted by the server. Why does this happen?