Recently got a 4S and love it. The battery life is surprisingly good even with heavy use. The thing is, my phone has started dying with juice still left in the battery. The phone will just shut itself off with plenty of battery left. This first happened with the battery at 7%, then 12% and today with 21%. When I plug the phone in and it restarts the battery charges normally but immediately shows the % it died at (starting at 7,12,21 etc and not 0). Any ideas what the cause of this is? Do I need to take it in to an apple/cell provider store? Really getting attached to it and hoping I won't have to wait another month to get a replacement.