oh, ok, sorry, I never thought that it could not be a normal behavior as he is not seizing or anything like that, he seemed to me as he was playing or looking at the top of the cage to see if he could find like a bigger space around, or he was trying to get my attention to take him out or anything, as after that he has never acted sick or anything, he just looked the same way as my other chins,
if you want, I can shoot another video of him playing around and show you guys, and let me know if you find if he acts normal or not when he is running.
I can also see if I can get him checked by the vet to make sure he is alright, even though I think he is, but he is not sick really, it would be more for a check up I guess, I will also ask the person I bought it from if he used to do that before or not, to get more info on the issue.