Dark spots appear in transitioning lock/home screen

When you guys unlock your iphone 5s screen using your fingerprint, do you see a really fast black spots on the top half of screen? Like during the transition between the lock screen and the home screen - it lasts about 0.5 second. The spots are not from water damage since I just got my phone 20 days ago and it hasn't touched water yet. This problem appeared after I updated to iOS version 7.1.1
I changed my background to a different color and now the pixels are white.


Settings -->  Wallpaper --> (select whichever image or photo you want to use) --> Set, choose Lock Screen, Home Screen, or Both