Yes, well, I only had 1 BTC there. The thief even left the withdrawal address:
1GRBm7iQMGsgWjHPSTcGBMTzQwhTWyPZMh
It looks a bit odd, because the attack was done somehow "from the inside" (because of the email confirmation that would have happened normally), but they did not manage to cancel a pending transaction. Leaving the withdrawal address is also a little amateurish, though it does not really help me.
On the plus side, this is why I only keep a minimum of BTC available on such exchanges at a time.