there isn't any mucus that I can see... it does look like there might be stuck shed since there are pieces peeling up, but I saw the whole shed intact including all the head parts... I just finished cleaning out his cage about 30 minutes ago and he hasn't been doing it since but I will keep an eye on him... ooh and he just yawned and it looked like it lasted a good 3-4 seconds quite a bit longer than usual