I had that same issue with mine, took to a local authorized Apple service center and they instantly knew of the problem. Dropped it off right when they opened and picked it up right after lunch the next day. They told me Apple switched to an only Samsung part number due to the LG screens having the retention issue, like the one I just had repaired. The Samsung screen was perfect, but a little heads up, LG screens tend to be very cool where as Samsung tend to be warmer, I prefer a warmer screen.
I'm just as productive on my rMBP as I was on my 13 Air, I find my increased productivity was due to SSD not some magical machine. Sometimes I do wish I bought the 13 Retina as I have zero need for the dedicated graphics, and some apps force dedicated even on just battery.