That's what I notice I exchange 4 or so and all have yellow tint I'm considering swapping it one last time and see if I get lucky, what's weird it's all the demo units at the Apple Store, Verizon, best buy etc have a nice cool uniform tint but only on demo units.
That is a little weird. Maybe the yellow tint wears off over extensive screen on times? I mean, the demo units' displays are on almost nonstop. Probably not, but just a thought.