There is a series of messages on the Apple Support Communities pages where owners of the new iPhone 4S are saying that their new phones are showing signs of a yellow tint. This is similar to an issue that affected the iPhone 3G and there are some users saying that it happened on some iPhone 4 models.
However, while there is no actual reason for this yellow tint, there are plenty of theories such as, it is only affecting the white model and that the tint could be from the glue used for the screen, which has not hardened fully and therefore will disappear with time. Nevertheless, there are users who are saying that the display actually does appear to be “Washed Out” and that cannot be a good sign.
As of yet Apple have not commented on these claims, so we can assume that if it is a glue issue it will fade away, other than that the Genius Bar at the local Apple Store is going to be pretty busy for a while.