I noticed a faint popping noise every once in awhile when using my nexus. Yesterday I realized it was coming from the speaker. I keep my phone in vibrate and shut all app sounds off but for some reason, the speaker turns on by itself and then shuts off with a popping sound (about 3 seconds after the speaker turns on). This happening to anyone else? It might be haptic feedback related cause it only seems to happen when the screen vibrates.