GUINEA PIG HELP PLEASE?!?

My male guinea, 2-3 years old, has just started lifting his back left paw while he's standing still. He can walk and run around fine, and he doesn't appear to be in any pain, he behaves and eats perfectly normally, but this only happened yesterday after my little sister and her friends were playing with him without my knowing, and when I put him back in his hutch I noticed he was lifting his leg. This was yesterday and it's still like this today, should I take him to the vet or will it heal itself?