My guinea pig is rumbling for no reason...?

Question

I should know this answer but just to make sure cuz i think hes just streching...but is he hurt or something?

Answer 1

Rumblestrutting is a common dominance move.

http://www.guinealynx.info/

Answer 2

do oyu have another piggy?

it will be dominace

Answer 3

if its a purring rumble, and he kind of 'vibrates' its often because he is content or he might want you to leave him alone, if he does it while  you are handling him. hope i helped.:D