I Bite the inside of my cheek?!

I Bite the inside of my cheek?

and i dont think its related to stress cuz imdoing it now and im not stressed at all..its just once i do it once I cant stop..HELP.

2 weeks ago
thank you to my best answer..it never occured to me that deep thought might have been the cause. but now that i think about it....it is.

i do that too, im not stressed either its just a bad habit i formed when i was a kid and i have been doing it ever since, my dad does it too. i usually do it when im thinking really hard about something though.