Moto X Pure grey rectangles on display

[MMMDDDZZZ]

I have transparent grey rectangles that appear over nav symbols at bottom of screen, very intermittently, and usually toward end of day, maybe when battery is lower. Have heard it's a display driver issue, known but no fix. Will Nouget fix this? Anybody heard of other solutions? I've rebooted, soft reset. Not worth doing a full factory reset - it doesn't affect functionality, unless the rectangles expand upward with time. These transparent rectangles flash intermittently, and sometimes are not there at all. A screenshot does not show them. Stock, with Marshmallow. Suggestions?