you are onto something -- I will certainly discuss this with GM as I think they should be vigorously addressing this problem -- I feel that GM - Customer Assistance is ignoring me.
My own experiment consisted of putting black tape on the minimal amount of chrome on the rear of the Terrain -- the white vertical line remained. My next expeiment was to create a lens hood like that on the end of a DSL camera lens. A promising result; then a cloud blocked the sun!
Another cause may be a failure of the CCD sensor. There are three areas that technicians at GM need to talk to us about -- the lens, the sensors, and the receiving unit.
Happy to hear comments from those affected or not as I think this failure of the camera will occur to everyone with 2008-2012 GM vehicles over time and for safety reasons the rear vision camera is important.