I originally had the blemish as well as a dark bluish band across the top on a device from September 2015, it was exchanged two weeks ago because the display became very dim, and a display replacement did not resolve the issue. The new one I received had a gorgeous display, no blemish, crisp bright white, unfortunately Siri was not working correctly on that device even after restore and setting up as new, they couldnt figure out if it was a single component to replace so they gave me a new phone again, now this one doesnt have a blemish but the screen is slightly dingier looking, just not as crisp as the previous phone. Also the first device was TSMC, the second was Samsung and the third was TSMC.