Nope. The only background checks I've ever had working for Americans was law enforcement / intelligence agency software (I was working for a Canadian company and they sold to them) and a contract for the Nasdaq.

Other than that, it's just been straight skills and reputation. Even if it did come up he could always say that he assumed they would ask for a background check if they cared about this type of thing. Just let the man get some work and move on with his life.