Solved! Go to Solution.
Sorry I managed to cut myself off earlier.
From what you describe it sounds like a bad connection between the display and the motherboard of of the phone.
It happens. the glue was not placed correctly and after the phone warms up things can shift.
Or it could be a bad display.
Not really a user serviceable item. If you can't return it you will have to deal with Samsung and warranty.
Of course it couldn't hurt to chat with samsung about this.