I'm on my second Air, first one had a dark blue tint down the left hand side covering about a cm in, second has the yellow tint over half the screen. compared it to my 4 and mini and they are uniform over the whole screen. The fact it's always seems to be the left hand side seems weird. Going to return it and if I can't find a good screen I'll get a refund and stick with my Ipad 4 for now, shame it's an amazing tablet in every other way.
I guess if I only used apps or sites that were very colourful it wouldn't be an issue but I use a lot of apps and sites with mainly white backgrounds so it stands out quite a bit. It probably wouldn't bother me as much if the whole screen had a yellow tint but the half and half makes it irritating.
I don't think I'm being over paranoid about it I've had a first gen Ipad, an Ipad 4, a Mini, Iphone 4 and 5 and this is the first time I've ever had a problem.
I saw someone mention (can't remember the site) that it might be the magnets affecting the screen, is that possible? If so seems like there won't be such a thing as a good Air.