Mine started doing that after I installed the leaked 6.1 ROM. It does it randomly on boot up, when the little windows theme is suppose to play during the green screen. Sometimes the music plays, and sometimes it just pops the sqeaker. I also missed alot of email notifications yesterday, because it just started popping. After I went into sounds and notifications, and reselected the alarm I use, it was fixed. I think it has more to do with the ROM, than the hardware. No problems with the stock Sprint ROM.
