My chin does this when my boyfriend gets home from work and we start setting up the room to let him out of his cage. It could be his way of telling you he wants more roam time
So my boyfriend and I recently took in his co-workers 10 year old chinchilla back in October and everything's been great. Just recently (last week) he started biting our pant legs and biting at our feet at first I thought he just started biting me because I scared him when I got off of my bed...