It's a good observation, but in this case I'm not sure how this could have felt like stalking, since he told me that he works at this other place on Saturdays for extra money. I've asked him about one of the T's there, to see if he knew her and could recommend her for me.
I know where he lives and works; he knows where I live and work. We've looked at each other's houses on Google maps (he was having an addition put on! My old house was too small and loud neighbors were too close!). He has a listed phone number and has called me at home from his house when the center was closed due to snow.

The "flirtatious" element was there for me, as if I was 18. I really regret sharing it now. It felt reckless to make the invite, since my therapy would have been destroyed if he had said yes, let's meet.

I won't know for a week if that is what he noticed and reacted to. Stay tuned.