Some users who took advantage of the bug and withdrew funds to their bank accounts found their accounts frozen shortly after, when Coinbase noticed the error and began working to claw back the funds.
Typical... and it's not the first time I see this happen. Usually exchanges freeze the customers accounts until they return what they earn on those trades. It's a bit shady... but it's probably covered in the small print in the TOS they have.
RE: Coinbase Cocks Up with X100 Bug