Rat biting at his own front paws?

[Tesslalala]

I'm not sure if this is behavior or health but I have a rat who's about 4 months old who's been pulling at his front paws with his teeth like they're itchy, he's does it pretty frequently and he doesn't seem to be doing any damage so I'm not overly concerned, it just seems odd. I have 2 others rats, both male, one of which is this guys father and neither of them ever do this. I have noticed that the bottom of both his front and back paws are somewhat blue in color but he is a white rat and when I took him to the vet last month for a respiratory issue the vet didn't seem concerned by it. And other than the pulling he really doesn't seem unhappy or uncomfortable in any way. I was just wondering if anyone knows why he's doing this and if there's anything I can do to help him.

 

[SQ]

Rats sometimes barber themselves, although that is normally on their legs, not feet
He may be bored or stressed so a huge cage with lots of interesting activities may help
Does he live with you other rats in a cage that is at least 6 cubic feet in size, and do they get along ok?

He could also be ill

Here is some info on barbering: http://ratguide.com/health/integumentary_skin/barbering.php

 

[Tesslalala]

Rats sometimes barber themselves, although that is normally on their legs, not feet
He may be bored or stressed so a huge cage with lots of interesting activities may help
Does he live with you other rats in a cage that is at least 6 cubic feet in size, and do they get along ok?

He could also be ill

Here is some info on barbering: http://ratguide.com/health/integumentary_skin/barbering.php

He has a double decker critter nation so it's plenty big and he lives with 2 other boys and I've never seen them fight. Maybe it is just a barbering thing.