IPhone 5 display is soft when pressed at the corner. Shall I return it?

When I press the display at the top left corner it bends a little bit and makes a sound (like it is not holding properly).It is not by much but rest of the display is rock solid. I have the phone for half a year now and I'm sure this was not happening when I bought it. I have never dropped it, I keep it in case and I use protective foil. There's no problem with functionality, the screen works just fine. I would tolerate this behavior with cheaper phone but 800 dollar device should not suffer from these issues.

There's usually a years guarantee on apple products, so if you go to the apple store and tell them, they should replace/fix it for free