|Is the black line very thin, thinner than a row of pixels? If so, then it's not a bug, it's a 'feature'. |
Look closely at the screen and you'll see a gap between two rows of pixels right in the middle. I believe this was put there during the design of the display so that when manufactured there would be a higher yield.
So, the long and short of it - if it's a line thinner than a row of pixels, every unit comes so equipped, if it's thicker it's not normal and you might be able to fix it.