What's wrong with screen of my 5C?

[905135]

I have noticed that it is going bigger. What is this? Touchscreen works fine and its somewhere under the glass

 

[iPad Retina]

That's is a weird problem.
Have you dropped it?
It could be like a Burst of extra light.

I would bring it into your local retail Apple Store, unless the screen has been replaced by a 3rd Party shop.

 

[rigormortis]

unless they can prove you dropped the phone, this should be covered under warranty