ISO 10011 states that the client should be notified when an audit will be conducted. I will admit, however, that there is a distinction in the term client. And, ISO 10011 is a guidance document. As Marc stated, be sure to check the contract before signing. Surprise audits are indeed rare, and would not be conducted unless the registrar suspected something. I suspect that if, during an interview or site visit, the registrar observed something that would make them suspect things were not on the up-and-up, then they may be inclined to send in an assessor unannounced.
As far as the original post is concerned, I suspect that the Management Rep is using this to try to intimidate persons within the orginization. I agree with Marc...a pretty stupid scare tactic.
Best Regards,