After updating to iOS 7, weird black spots on screen?

I updated to iOS 7 the day it was released, and I immediately noticed some very weird colouring when the screen is black.

It's most evident when I receive a text message. The background should be a uniform black, but there's a "blob" that's a completely different shade of black near the center of the screen. It almost looks like someone depressed that particular area of the touchscreen too much. It's difficult to describe, but imagine pressing a computer monitor and seeing the colours go all whacky. It's like that, except the only colour is black. Hopefully I'm explaining this in a way that makes sense.

Normally, I would think this is a hardware issue, but this never happened when using iOS 6. The screen is perfectly black when the phone is off, too. If I open the camera app and cover the lens, the picture is perfectly black/uniform, so I don't think the problem has anything to do with the physical touchscreen.

So... is this a bug or what? It's very ugly and makes the phone look defective. Any help would be appreciated.

EDIT:
I just checked the compass app (black background), and no issue there at all. I think this problem might be specific to the messaging app since I only really notice it when I receive a text message.

Oh, and I'm using an iPhone 4S.

swordfish5736 said:

Do you mean when you receive a notification on the lock screen? What does your wallpaper look like? when you get a notification on the lock screen your wallpaper is blurred underneath that notification.

Click to expand...

Aha!

My wallpaper is a picture of my black dog, centered, which likely explains the anomaly, lol. It makes it look like I have a defective touchscreen.

Wow, yet another reason to dislike this fading nonsense. I hesitate to ask whether I can turn this off since I know we're talking about Apple here...

----------

Actually, I want to make sure I'm understanding this properly...

My wallpaper is a black dog on green grass, but everything is blacked out when I receive a notification. Is it the black on black that's causing the colour to be non-uniform?

Paddle1 said:

You actually can turn it off in Settings.

Click to expand...

Where? How?

So much simultaneous posting, lol. Thanks for the help guys!

I increased the contrast, but haven't noticed any visual change to most functions (a good thing). Now I have to wait for a text message to see if this worked. Fingers crossed!

I just received a text message and the mystery is solved! Thanks again for the speedy replies.

I actually prefer the high contrast design. It's less busy and easier to read. At this rate, I'll be drinking warm milk and wearing Depends in no time!