Re: iPhone 5 vs 4S LCD difference
I don’t think there’s a lot to worry about. First of all, the early releases of the iPhone 4 and 4S all had an issue where the adhesive that was used to attach the glass to the screen had a bit of a yellow (or warmer) cast to it until it was completely dry. I believe that some of the iPads had this issue, as well. As soon as the adhesive was completely cured (sometimes it took as much as a week), the screen color changed to something a bit "cooler" color temperature wise. The cause of this issue with the early iPhone 4 and 4S models had to do with supply and demand, and the fact that the phones were being rushed out to customers before the adhesive was completely cured.
Originally Posted by gameson
I don’t know if that is happening again with the 5S/5C screens, but certainly it is a possibility, given the popularity and demand for the devices.
There’s also the possibility that a different manufacturer was used to supply the screens for the 5S and 5C, and that, in fact, these do look "warmer" in color than your old iPhone 4/4S. It may just be how it is.
Regardless of the reason, if you are not happy with the screen, you can visit an Apple Store Genius Bar and have them take a look at it. If there is a problem, I guarantee that they will resolve it to your satisfaction.
Good luck, and let us know how this turns out.