I have seen a similar issue with other touchscreen devices. Most manufacturers offer a calibration program that is supposed to fix this issue (supposed to but doesn't always for me). Make sure the screen is cleaned properly since grime and dust can sometimes mess with the capacitive touch detection. Sometimes if you turn it off and clean it then use gloves or a thin cloth to configure the touch calibration it is less sensitive to atmospheric changes and statically charged dust. This can also be caused by a screen fault that necessitates the replacement of the screen (or you can just turn off the touch part of the display). I have sent so many devices back to the manufacture with this "Ghost" issue and it's never consistently clear what causes it.