Upper right corner creaking when pressed

There are small tabs at the top of the display that align with the rear housing unit, and there are 2 screws on the bottom of the unit that hold it all together, but if the taps at the top are stretched or misaligned, then it would feel loose to the touch... But there is a very small rubber seal around the edges of the display that act as a bit of a suction when the display is pushed into place, so it should be rigid when its fully fitted.

If its loose at the top right, you can remove the two screws at the bottom and use a suction cup to pull the display up from the home button side (be careful as the LCD and digitizer cables are pretty short on the upper side, so don't tug it), then reseat the display making sure the plastic tabs at the top are seated properly into the rear housing.

Other than that, you'd want to take it back to apple to get it exchanged, as it is a manufacturing fault from the sounds of it