I had this issue fixed on my mid-2012 15" rMBP. It's known issue with some of the early LG panels on that model. The technician at the Apple store ran some standard image persistence diagnostic script to replicate the issue.
They replaced the display for free outside of AppleCare. I didn't have to argue with them at all, so I suspect that this is their standard response. YMMV if you have a newer model.
They replaced the display for free outside of AppleCare. I didn't have to argue with them at all, so I suspect that this is their standard response. YMMV if you have a newer model.