I'm sure I'd feel awkward about that as well. But my T said he runs into about a client a month while out and about. He says he's often busy doing whatever it is and might not notice the client unless they say hi or wave. (The client might tell him later that they saw him.) So it's possible she didn't notice you, even though you think she did. I'm not as concerned about running into just him, but if it was he and his wife and/or his son, I'd feel much more awkward. We only live about 10 minutes from each other, so I feel the chance of running into him is relatively high. Though hasn't happened (to my knowledge) in past year and a half, so maybe not? (I've so just jinxed myself here...)