What the subtext says to me is that the assistant director, or whoever OP talked to, was well aware that OP was just some rando passing through, (probably through experience working in cities), and not a unionized member of SAG. The “nice work” comment was an opportunity for OP to say, ‘uh huh’ and float the director enough plausible deniability to salvage the shot. As soon as he said, “no”, it’s cut and reshoot. Probably not a big deal, but worth a shot (pun intended) from the director.