Yesterday I was using my Glo in bright sunlight (in temps around 27c) and a couple of hours later a faint vertical line appeared exactly half way across the screen. It was virtually invisible when reading without the light but jumped out of the screen with the light on or when refreshing. It was also very visible on the homepage, slashing the tiles.
No matter how often I refreshed the line wouldn't shift. I was pretty upset as I love my 3 month old Glo & wasn't looking forward to the hassle of trying for an exchange (I'm based in the Netherlands).
After reading this thread about the lines being caused by heat, I popped my Glo in the fridge for 20 minutes or so just to see what would happen. When I retrieved it the line was gone - completely gone!
I'm going on holiday tomorrow & the Glo is likely to experience more high temps. It will be interesting to see if the line re-appears. But for now I'm a happy-bunny.