No I genuinely hold it normally, I go to the gym but I'm certainly not that strong. Just holding it now in bed, if I hold it how I find comfortable I lose signal and data, I can hold it so it doesn't lose signal but it's not very comfortable. This is my issue that I have to hold a very expensive device in a way that doesn't suit me. Obviously within reason before people think I mean the wrong way round, upside down etc etc.
Maybe it's faulty although the guys at the genius bar wouldn't offer to change it. I have a bumper from the free program they did but it has scratched the metal band on my phone making it look bad
It's also a shame to have to cover your phone up. But yes with the bumper on I do not get signal issues holding it the comfortable way, but I have to ask why do I have to have a bumper on to make it work?