The best response is no response. All hobbyists should be ready for this type of situation. When you meet an SP outside of the hobby, you must act as if you had never seen them before. For your sake and theirs, the hobby must remain secret. The only exception to this could be if you found yourselves utterly alone together and were assured of privacy. In that case, you could bring up the past relationship. I have been in that situation (more than once and one time was the opposite situation, where I knew the woman in a business situation then was introduced to her in an SP situation) and had to act. I would also say to Slithery that you could easily have said to your woman friend about the waitress "I don't know where I may have met that woman before but she looks familiar. I guess I look familiar to her too"