Same here -- left side a noticeable yellow tint and right side a noticeable blue tint. Pretty distracting from an otherwise amazing screen upgrade resolution wise. However this will be enough for me to ask for a replacement after a week if it remains. I'm fine with either tint as long as it is slight and, most importantly, uniform.
So I took it back this morning. I asked the Genius if he could see the gradient from left to right. It was subtle to him, so he took it to the back for a couple of minutes and consulted with his colleagues. He returned and agreed to swap it out. The new one is uniform, so I'm happy with it.