Recognized Kevin, AA purser, NRT-LAX (or maybe -SFO) in J after he took excellent care of me a while earlier ORD-LHR in F. In the FT tradition, both flights were on the cheapest possible tickets with upgrades. For ORD-LHR, I used miles to get into J and then got an operational upgrade to F.
I also recognized AA FA Donna BOS-LHR. That wasn't from a previous flight, though. Second officer Kent had made a video about what happens during a trip for his family and posted it on YouTube. I learned of that video on FT and downloaded a copy to use in my classes (with his permission), so I had watched it several times and recognized her as one of the FAs who appear in it. She knew that he made the video, of course, but she had never seen the finished product. I had it on my laptop and showed it to her. (That flight was also on a cheap Y ticket with a double upgrade.)