Today i juts got the first rechallenge since the latest fix.
I have currently open the challenge window (and the trading robot is out of game).
I will let you know if this happens again.
Make sure you are not going back to the problem...
Tom
PS I dont know what kind of gimmick you are doing server side, but note that it should be physically impossible to rechallenge the user until he restarts the gateway/tws. If you introduce the simple flag as i suggested, relogging with the stored good credential there will be no way this problem happens again.