This morning I was defrosting my rear windshield, and I noticed that the top 3 or 4 inches was not defrosting. I took a close look at the glass, and there are those orange wires running through that area, which is basically the top where the glass is darker. The rest of the rear windshield (from the dark tinted area down) was defrosting fine. I never noticed that the top didn't defrost before, but I'm hoping it is supposed to be like that and there is nothing wrong with the car. Any ideas?