If l lay my phone on the table, and just use a finger to press on the back/home/square buttons, the phone won't do anything. If I touch the silver parts of the phone (say the top part where the camera is) with my other hand or fingers, then the Android buttons would work again. I also find that the Android buttons become less sensitive, if I am just holding the keyboard and the back synthetic leather parts of the phone, without touching any silver parts.
Do you observe this issue on your phone as well? Or is it just me?