I asked my old T about that, since we were on a college campus and the likelihood of running into each other outside of the office was fairly high. He said that if we were both at a social event, he would leave it entirely up to me how to respond. If I was uncomfortable being there with him, I just had to give him a sign and he'd leave. And nothing said or seen there was fodder for our sessions unless I brought it up.

Luckily, that never happened. I only ever ran into him walking across campus and we were both alone.