I have the same issue occasionally, too. I thought it was just me. Every so often, it's almost like using a resistive screen - you have to press things multiple times to get it to register. Then once you unplug the phone everything goes back to normal. Seems to happen to me when I have the phone plugged into my laptop to charge.
Someone mentioned not having this issue with an official charger or wall charger (not the USB and ac adapter) and I'm not seeing it right using an actual ac charger.