goaliee: I left the room I then noticed 250k had been removed from my total
See Tram's reply above...
In addition, if the game has matched you with an opponent, just before, or right at the time, you hit the back arrow, you will still be charged the coins and your "unknown" opponent will see that you forfeited on their screen and win the coins.
So, if you are going to cancel a coin room game, you have to do it pretty quickly.