Clicking coming from body?

First off, I highly doubt it is a respiratory infection because the clicking is not coming from his breathing or mouth.

For a couple of months now I've noticed something odd. If I place my thumb on the top of my BP's back and my index on the bottom and slowly run my fingers down the length of his body I feel (and hear) and odd clicking noise when I get towards the end of his body.

Viv temps range from 79F to 92F
and the humidity stays around 51-56%
He eats perfectly fine, sheds fine, is pretty darn strong, drinks a lot, etc...

It doesn't seem to be causing him any discomfort, I haven't noticed any changes in his behavior, but I just want to know if it's something I should be worrying about or not. It's not affecting his strength either, he can easily pull his body up even if he's hanging onto something with just his tail.

This is the area where the clicks come from. It doesn't happen all the time and only seems to happen if slight pressure is applied to the region. (also this isn't my BP)

http://i911.photobucket.com/albums/a...psiw7su6ix.png