Casio GX56 question.

I've just received a second hand GX56 and have noticed a couple of things that seem a bit off. Firstly when in the 3 button screen the module reads as 3179 not 3121 as on the backplate. Secondly in a certain light the screen looks slightly distorted almost like acrylic when it takes a knock. The screen is definitely glass with no signs of damage. Any thoughts?

Cheers Ed