I am going to take my iPhone into Apple tomorrow morning. I can't seem to hold on to a call for more than five minutes, and I have kept my hand away from the lower left. In fact, when I do drop the calls, I see all five signal bars full. Also am having trouble with Facetime stopping at around the five minute mark as well. I am kind of afraid to trade in my phone, fearing that I may get something worse, like people who have proximity sensor problems, or yellowing screens (they're perfect on my i4).