We have some gliders that just groom hard.
Maybe he has some other scent, animal, food.
Maybe they even feel he NEEDs the grooming.
I have some newer gliders we picked up from another owner, they are getting used to us some and the male starts to lick my hairs on arm, then starts to pull them like super hard. really hurts.
I would give them some more time, some of ours would put our hairs hard or nibble our skin between their teeth pretty hard but stopped over time.