Iphone 4 Screen - Fake One ?

Ok, so i got a new iphone from a cellphone provider in my countrey (Israel, Pelephone.)

And it seem's like iv'e got one with fake screen ..

there is a picture :

As you can see there is like a small rainbow in the bottom of the screen .

This thing happend's when a big source of light is hitting the screen..

Like its a plastic screen and not glass \:

-IMPORTANT : MY SCREEN WASN'T REPLACED, THATS THE WAY I GOT IT FROM MY PROVIDER . -

as more the light is stronger the rainbow is more visible and bigger ..

It need's to be like this ? its ok ? im freaking out for nothing ?

This is really important, thanks for the helper's 🙂