When I first read this I thought whatever. This has to be made up but to my surprise I can duplicate this perfectly. When my phone is in my hand or a hard surface the screen responds excellent. When I place my phone on my soft coat it stopped responding. I am really amazed. The Samsung device is a really great device and works great but the screen does stop responding when placed on a soft area.
This explains why when I'm at home developing my phone seems to stop responding so well. It's because I lay it down on a piece of cloth to "level" out the back so when I touch the screen the phone doesn't wobble. It must be soft enough to make the screen to become a little unresponsive.