Mouthguard

[boomer in clc]

During game, one player who was wearing a mouthguard would move it in and out of his mouth with his toungue during breaks in the action. Referee said he did not want to see the mouthguard again. Player moved mouthguard again (probably a nervous habit). Referee made the player remove the mouthguard for remainder of the game.

I had never seen a ref ask a player to remove protective equipment and wanted to know if there is a new rule in place or is this just a pet peeve of this particular ref?