Door frame hot and discolored between freezer and fridge

Hi,

We bought this KitchenAid 42" builtin model used several months ago and noticed some discoloration on the door frame between the freezer and the fridge. The area is also warm to the touch and has some hiarline cracks in the liner.

Any have any ideas as to what is wrong? My thought is that there must be a heater in the door frame and it’s not getting turned off or something.

Thanks!