iPhone 6S grayish/dim toward top

[macjoshua]

I've gone through a couple iPhone 6S's, and both have had a darker, grayish tint toward the top. The first was very dark toward one of the corners, but the second is much more of a 'gradient' look from the top to bottom of the screen. Is anyone else seeing this, and if so, has it lessened much with use? I already had to swap the first one right off the bat because of dust under the screen (that one didn't have the darker tint, sadly). I just want off the exchange wagon!