The teller helped him structure the transaction so in some way's you leave yourself to helping the client become suspicious.
The amount of cash in your account has nothing to do with the value of a relationship. The teller told him he needed $2,000 and he put that much in. Obviously he didn't want to do that originally or he'd have filled out a deposit slip.
The average balance and legnth of relationship are how you should have judged the ability to deposit without hold (or collection). Going on cash that is not held is silly.
So yes, he sounds somewhat suspicious, but heck, ya'll helped him get there by structuring him into the deal.