somebody's gotta pay... if that check isn't legit, where's the $5k come from? the bank, that's who. And they are going to want their money back.
As threadstarter said, he's going to wait and see what happens. It's not like he went to the corner store and cashed it. It the money appears in the account then it was drawn on an account with funds in it. They don't do 'deposit with cash back' on a $5000 check.