I have an iPhone 5 in black, but it has a yellowish spot on the screen.

I have an iPhone 5. I got it last Monday April 15th. I got the black one. After the first day I noticed there was a small yellowish spot in the top left corner of the screen. It hasn't went away. Today I am going to call apple to try and get a replacement since its still so very new. But I am also wanting to switch to the white iPhone 5. Because I want it to match my ipad. And because I don't like the black as good as I thought I would. Do you think apple will let me? And if they do should I switch to the white?