Caleb, my only male, and who is neutered is a recent addition to my glider family. He is really sweet, not afraid of me or my hands. However, he like to lick on me when my hand is in the pouch and accepts my hand being there with the other 3 girls. He will even crawl up into my hand and move the girls out of the way to get into my hand to sleep. Sometimes, he does a lick, then a nip, like he is trying to "groom" me, but the nip is awful hard. I offer treats and make the psst/ tsk sound, which he could honestly care less and the nips get harder and harder. The other day, he was rubbing his teeth on me--not nipping--and took off quite a bit of skin on the back of my hand in a couple of locations. I stuck it out as best I could, but enough was enough. When I pulled my hand out to see what he had done, the wounds looked like the back of my hand ran across a potato peeler.

This was not an aggression, no noise, no lunge, just rubbing teeth on me. Any ideas if this could be him trying to assert dominance over me, or perhaps is he just a very rough groomer? My girls do not do that at all, sometimes they will pick with their teeth but not in any kind of a painful way. Caleb, on the other hand will put his teeth and pull at my skin.

If it is a dominance thing or otherwise, has anyone here experienced this and is there a safe way to break him of it?

Well he has decided that you are one of the colony.

When he does this behavior you should try hissing at him, that would be how another glider would communicate to knock off that behavior.

I have also blown on them to get them to stop that behavior.

You need to distract them or he will continue to groom and they like to remove bumps, lumps and scabs. Anything they think doesn't belong they will try to groom off of you.

I agree with Feather. Scented soap, or if you've handled food may cause him to 'taste' it. Offering mealworms as a distraction only encourages bad behavior.