So in that context, I am used to running into people who know confidential things about me, but I feel safe that they are bound by ethics not to say anything. I understand the boundaries re social interactions.
if I saw my T in a restaurant, I'd probably give him a tiny wave and ignore him the rest of the night. I have seen a past T in the shops, we've given each other a tiny smile but kept walking.
Same with my GP and interpreters. I acknowledge them, but don't approach them or socialise with them.