Blue tint at edges of iPad mini retina... possibly..

I keep seeing this blue tint at the edge of my iPad's screen, a few mm wide. It's most noticeable on the top edge by the camera, and especially against the grey of the keyboard. I can't see it at all on the bottom edge. Sometimes I'll look at it really close and be unable to tell if it's there or not, but when I switch back to reading I can see the vignetting out the corners of my eye. It's only visible at medium brightness settings. Nobody in my family can tell it's there. Am I going crazy?

edit - I just tried to take photos, blue tint doesn't show up at all.

 

When I'm not working hard to see it, I can see it easily. If that makes sense...

 

I think it's likely they'll turn me away and I don't think I could bear the embarrassment. Thanks anyway.