So my new Dexcom arrived in the mail this morning and I inserted the sensor myself (yikes!), and it seemed like everything was going OK for five or six hours, but now it's going "???", with a few minutes of an out-of-range symbol even though it was in my pocket. Did I maybe put it in wrong? I know the loaner I had last week was very dodgy the first day, but I don't remember seeing ???. Is there a…