Ive seen this problem on the gel but never on stock.
Try changing your wallpaper to another stock one and see if that fizes it. If not, go on the internet and find 1920x1280 wallpaper files that you like. Then go into the gallery, view the specific pic, hit the 3 dots,set as wallpaper and crop to your liking.
Hope this helps!
What if i told you
android is superior to ios