I'm not sure why yours is doing this, but I have seen this and many other odd behaviors. I had a retic years ago that had a facination with one water bowl. He would stare at it all day. I saw a king snake that repeatedly bite his tail and attempt to constrict himself.
For your's I guess just an urge to borrow. If the inside of his mouth is clean, and you don't see anything outside, maybe just add some substrate to see if he just wants to bury and hide.
Good luck
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Why does everyone still believe the world is round, when we know it is flat?
(Me)
1.3 Bearded Dragons Eenie, Meanie, Minie and Moe is the Male
2 baby female Western hognose, 2.3 adults some friend some mine) All Named George
Corn snakes
bloodred 0.1 Christal Blue Persuasion
earthtone 0.1 Wind and Fire
creamcicle 0.1 Sherbert
Amazona ochrocephala oratrix 0.1? Pretty Girl
Amazona ochrocephala auropalliata 1.1? Carol - Male, Foghorn Leghorn - Female
Amazona aestiva 1.0? Miss Prissy
Ara ararauna 0.1 April
2.0 Dogs, Michigan, Doc
0.2 Cats,, Sassie and Spooky (all black cat)
0.1 Wives, (Long term captive!,, I mean ME!) I call her (BOSS)
1.1 Kids (Paininthearsius takamemonii) J/K great kids
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tom
www.herpzilla.com