Thanks for the answers.

I give the FAMs a good bit of credit for not asking for ID (or detaining you to run a check etc.) In this crazy era where people tend to think flashing a piece of laminated paper with your photo and name somehow proves you aren't "bad," and where the airline business is obsessed with checking passengers against secret blacklists, it's nice to see good non-intrusive police work carried out through a friendly convesation without the ID obsession.