I would think so - am not sure how Bitstamp works but generally once your funds have been credited to your account the UTXOs are *theirs* to do with as they please (i.e. they don't *host a wallet* for you) so spending of those UTXOs (which could be movement to cold storage or simply a withdrawal for another account holder) is to be expected.
If your balance is not displaying the funds after 6 confirmations then you might need to check with Bitstamp support that nothing has gone wrong (could just be some sort of delay on their end).
thanks, yeah my balance is fine. It's just the RED "unconfirmed transaction!" popped up with it's "-" symbol and scared me a little while I figured it out.
I can only assume that it is exactly that. Bitstamp moving the funds where they see fit.