I just got two iPad airs and I definitely notice the warmer tone of the screen in general, and it is an uneven tone from left to right. I'm also noticing that unless I'm really looking for it, it's not very noticeable, at least on my screen anyways. It also depends on the lighting of the room and the viewing angle. If I tilt the screen, the yellow seems to go away. Maybe this is another one of Apple's "you're holding it wrong" bugs. 