Does any one else's Guinea pig do this?

I know I post a lot about my piggies but frankly I can't get enough of them lol. So I have two little boys a Texel and a Rex who have been together since weaning. They have a large cage which consists of an indoor cage with a big C&C cube extension on it (and a little ramp) so they can exercise. Every evening I pop in their leafy greens and they come out into their extension while I sit there and they munch away but in between munching the Texel runs round his cage squeaking and jumping in the air! There doesn't appear to be anything wrong with him and he doesn't have fleas or mites. Is he just happy? Does your pig do this? It's so funny to watch lol =]