Can't believe how many posts I see who are returning perfectly good Ipads for the smallest of reasons.
Thing is once you use the Ipad you don't notice the colour difference. All you are doing is opening new Ipads and wasting them and no doubt will be back on the market as refurbs in a few months.
The colour tint isn't a fault it's been common since the 3GS > 4 change the screen looks warmer.
Sounds like you're just trying to justify not returning your defective ipad.
People are entitled to return as many as they see fit.