I understand your anxiety here just a couple of questions myself ,
How old is the set please?
How thick/thin is this orange line also is it vertical or horizontal?
OK one foolproof way of proving if its the panel or not is to press the menu button of the sets own remote control (when the line is present)and let me know if the line is OVER or BEHIND the menu display
The panel can go intermittent so the line can come and go but if you do that test we will know for sure