All the iPhones are not having the same screens since it's not only one company which produce the screens for Apple, there are 2 different companies which produce the screen part for Apple iPhones, thus you will find that there are most of the time, some iPhones with a whiter screen and some with a yellow tint, is it an issue? perhaps but whenever you take it to apple store for a replacement, you will not be able to prove that your screen is having a yellow tint simply because the light they have in the apple will prevent you to prove your point. This happened to me with my old iPhone 4, i ended up living with it like that. But you can always try to go to apple and see, they might understand your concern and agree to help since this is a known issue and is everywhere on internet too.
The yellow tint and dead pixels are known issues with iPhone 4 that being said you shouldn't have any problems taking it in to an Apple store. You could also call 1800myapple in advance and see if they can open a ticket for you.
The iPhone "yellow tint" is a nebulous issue. It varies with the lighting where you are and the screen data you're looking at. My iPhone 4 "seems" yellow at times, in certain situations, but then looks normal in most other lighting situations. You'll have to live with it for a while to see how it varies, and if it really is "yellow" all or most of the time, then the Apple Store is the place to go for a replacement.