Steve,
You can also see two hands with the two fingers in the Shock Wave ride from one person. I didn't know precisely, but I always thought that it was a way of expressing happiness in you taking their photo. So I looked it up a few minutes ago. It has historically meant victory or peace, but now has extended to show happiness. It apparently is popular in Japan for photography poses and has extended its use throughout the world. It's also a sign of friendship. It seems more popular with the younger generation from what I have observed.
What had happened in this case, is that I was walking straight ahead occasionally take photos. I noticed to the right of me, the one on the left side gesturing with the two fingers. I turned towards them both and snapped the photo. At that moment, the girl on the right side had smiled. She also had made two fingers that are lower. I think she may have been a little surprised that I would take the picture. But I'm not shy around people, so it was an easy thing for me to do.