Maybe he got them from work and they're supposed to go to employees only, or for salesmen entertaining clients, won them in a raffle, etc. Plenty of plausible reasons that he might act shady. Also, selling stuff on Craigslist is the only chance most people get to act like a CIA agent.
"You wait in the car. After 4 minutes circle the block once and come get me. If anything goes wrong, I'll turn my hat around. If we get split up, we'll meet up at the Whammie Burger later."
Where this guy works there is no client entertaining or raffle going on. He works in a "wherehouse."