Today for no apparent reason I shaked my iPhone 3GS by my ear to hear a clicking sound on the down shake. I wasn't shaking hard or anything this is my first time owning an iPhone so i'm just wondering if this is normal.
Could be one of two things. It could be your silent/ringer switch is loose. Or it can be the camera autofocus mechanism, which is normal if you tap on the back of the device near the top. Every single 3GS has that when tapped. You shouldn't hear it by simply shaking the device though.