Yesterday while using my phone it turned off when it said I had 15% battery. When I tried to turn it back on the battery icon came on telling me connect it to power. So I plugged it in and it came on and I let it charge fully. Today while I was using my phone with 28% left it did the same thing and wouldnt let me turn it back on until I connected it to power. So when I plugged it in my phone came back on and I took it off the charger and hasn't turned back off.. Yet. Any one have this happen? Why is the phone turning off when there is still battery left? Do I need a new phone? Bug?