I know the noise I'm going to reference is the camera autofocus, but I didn't notice my S4 make the noise and I know they have the same camera. If you are looking at the screen and shake the phone at you(forwards and backwards) do you hear a rattle? I don't hear it if I shake up and down or side to side. Anyone else. I just want to make sure it's normal because I don't hear the similar noise from my S4, HTC One, or iPhone 5S*although the iPhone has a very loose power button