They aren't scanlines, we don't have scanlines on flat panel displays, only tubes. They are just Gaps, why is this a surprise to anyone here? Press your face up to your flat panel TV.... guess what, you can see the gaps between the pixels!!!!
In 2D mode you see all 800 pixels with no gaps because they are close together. If it bothers you so much that you can't see the gaps, set the 3D ON and stop complaining.
If you compare it to the bottom screen, you're getting more that twice the amount of pixels in almost the same space, would you like your top screen to be more than twice as wide as the bottom screen?
Not a surprise. More like a complaint/.