Lol, interesting scenario. Well if he really had devious intentions I doubt he'd be ethical enough to treat you to Mc'Ds. Well in the end he notified you that he canceled the deal after treating you. But its always good to be careful and not paranoid. Maybe the guy was just eccentric, it is quite suspicious for someone not to bring the cash when under COD (Cash on Delivery) terms.
Well just my two cents.