About 50% of the time when I turn the phone off or put it to sleep mode with the side power button, I can hear a creaking/rattle near the vibration switch. Initially I thought this was the leather case making the noise. I took it off and the phone itself is making the noise. Anyone else have any issues with this? It doesn't prevent me from using an otherwise great phone, but I wonder if there is a gap in the screen or defect in the aluminum causing it.