So lately, my battery percentage has not been accurate, or my battery itself is been crazy. Yesterday, I saw that my battery is only 13% so I plugged in my cord to charge, and the percentage jumped to 21% instantly from 13%. Today, my battery was at 16%, and supposedly it should still last for awhile depending on my usage, but the moment i took a picture it shut itself off and I couldnt turn it on again till I charged it. Should I be concerned of this? It's a 16GB contract-free iOS6 Iphone 4S thank you!