Do you plan on taking yours back to Apple or just live with the clicky noise?
I think I am going to just live with it because it only clicks sometimes and I will not take it back until someone answers the refurbished or new phone question because I would rather live with the clicky noise then get a refurbished phone.
I noticed this as well - this has been explained by multiple Apple Store Geniouses as being 'normal' (supposedly it's the vibration mechanism inside the phone).
I have noticed the same thing on 4 separate phones (I'm actually taking delivery of my 5th 64GB today due to repeated cosmetic issues).
Others have had issues with loose batteries.