I suspected this may be a thermal problem at least partially after noticing it got much worse when I was charging the device and using it at the same time. It gets hottest when the battery is in the first half of its charge cycle. I grabbed an ice bag and put it under the device and within a couple minutes, the problem was greatly reduced or gone. I removed the ice after I felt the coolness on the surface of the glass. After about 10 minutes, the problem returned, getting worse as the unit heated.