To all saying this is intentional: Lets talk again in a month.
This happens EVERY TIME!!!! People claim it's intentional, and the screens are now correct! iphone 4: intentional. Few weeks later: blue screens. 4S: intentional. Few weeks later: blue screens. iPad 3: interntional. Few weeks later.....getting the pattern here?
I cant believe how many times people have tried to convince themselves that Apple is trying to "move to a correct color calibration"! If that was the case, the screens on all Apple products would have been slightly yellow since the 3GS! That was my first experience with this, and yes everyone then claimed it was intentional! But alas a few weeks later the good screens returned.
So go ahead and convince yourselves that THIS TIME Apple is really moving to a warm calibration. Just ignore the 6 other times this has happened, and yet, Apple returns to the "Incorrect" blue screens every time.
I guess you aren't a fan of reading technical articles about display colors. Overly blue tints (although you may like them) are not desirable for accurate color reproduction which is what makes a good display.
I have went through many 4S phones from initial launch up until just a couple months ago and they all had relatively warm displays compare to the iPhone 4. So my experience debunks your claim that they push the "blue" displays later.
However, should 6 months later we see nothing but overly blue tinted iPhone 5s, I will bend down and worship you as the display tint pattern expert.