grunting?

for as long as i can remember my rabbit has grunted 99% of the time, when she's just breathing, moving, lying down. its not an agression thing as its all the time. Never really been an issue, its just after being with my friends rabbits today i noticed how quiet they were!

any ideas?

Has she had a vet check?

well she's been to the vet for other things and the vet never said it was an issue, and as she does it all the time so i know she would have done it at the vets.

My wonderment would be a slightly malformed respiratory tract in someway and likely a predisposition to respiratory issues.

Also, if she is overweight, that might exaccerbate it more, as might dental issues. Respiratory tract infections could also do the same thing.