Since the beginning of the week, I've noticed that my iPhone4S' lock button just doesn't feel right anymore. Usually, you feel sort of a click when it's pressed. Now? The button still presses down, and the phone does lock. But it feels as though it's unresponsive. Almost, spongy. [Does that make sense?] Now, I like all my devices to be perfect. - Is it worth taking it to an Apple Store?