Iphone 4 rattling sound when tapping near camera lens

[Wessy]

My Iphone 4 started making this rattling sound when you tap near the camera lens. It also rattles when you get a text or call while on a call. I think it's annoying and shouldn't happen but brought it in to the Apple store and they said it was normal and that they all did it. He brought out a loaner that was worse than mine. Otherwise it works fine. Should I go back and demand a replacement?

Wessy

[Cowboy]

Mine doesn't do it could just be the vibrator though.

[iWieduwilt]

It's the sleep/wake button. Many people are having this problem with their i4s.