iPhone 5 screen became pinkish (warm white), except corners

Hello, everyone. Today I noticed that my phone's screen doesn't display the same color evenly. It's very difficult and nearly impossible to notice. Best way to see it is on white background. Normal screen's performance (let's call it white balance) is accurate only at all for borders. As it screen has an inner rectangular with warmer (pinkish) color. See it for yourselves (press on photo to see in full resolution and top quality):

Direct links to photos on my dropbox:

1. https://dl.dropboxusercontent.com/u/16547519/WebShare/iPhone5_Screen_issue/IMGP0 105.JPG (1.7 MB)
2. https://dl.dropboxusercontent.com/u/16547519/WebShare/iPhone5_Screen_issue/IMGP0 106.JPG (560 kB)
3. https://dl.dropboxusercontent.com/u/16547519/WebShare/iPhone5_Screen_issue/IMGP0 107.JPG (604 kB)

I'm gonna talk to Apple Care and will update this post in a few days. If anyone has or had the same issue, please share your experience. Thank you.

P.S. My phone hasn't been dropped or damaged in any case that could have affected this issue.