Thanks Murrellington. It was the first time that I had done such a thing. I don't remember where the idea came from, but as I watched them it just came to me. When my wife and I talked about it afterward she asked me why I didn't want the waitress to tell them who did it. I explained that such a gesture is not about recognition. That very simple act for me could mean a lot to them. Years from now they may still tell the story. Who knows? You never know what something you do (or say) may mean to someone, but you'll always know what it meant to you.
A different way to look at such things is "When is the last time you made someone's day?"
Steve