I don't believe in keeping secrets from your T- only when you're honest with him/her it can really work (otherwise why bother? So many things I could do with the money instead...)
So yes I also think you should bring this up in therapy- could have been him driving by, seeing you and turning to see it's really you (but I don't understand why he wouldn't have stopped and say hi) or it could have been anyone else (that I think it's more likely) but you can never know unless you'll ask.
Plus it's pretty common for a client to develop 'T crushes'- T should be use to that and deal with it accordingly (and professionally)- no reason to feel ashamed (easier said than done, I know).