Is this just a case of nerves?

I was just wondering. I sing in church occasionally. I get so nervous when I do. Everytime I do, I can tell my right leg starts shaking and I can't control it. It eventually stops, but it is very noticable. Could this be a seizure of some type? or just nerves? I have always done it.

I occasionally sing in church and I know that for me it's just both legs. I'm serious here. Next time you sing be aware of if you're tightening your butt. I do and if I relax my butt my legs don't shake as bad!

Thanks. Maybe that will help.