I've recently noticed that when I tap on the part of my iPhone 5 display near the volume buttons, the display feels like it is bouncing up and down ever so slightly. This doesn't happen on other areas of the screen. I also looked closely at the phone but nothing looks amiss. There's also a rattling noise when I tap on the lower left hand corner of the display. Seems to be from the camera. Or maybe it's the vibrate motor. Any ideas? After 7 months my phone has held up pretty well overall.