I have a mid 2014 MacBook Pro Retina 13", which was purchased in March 2015. In June 2015, I noticed a single bright spot mura located about 1.5" above the F7 key. I called Apple Support and reported the screen defect. Apple Support was excellent and only wanted to confirm that the defect was not dead pixels (dead pixels may be indicated by their geometric/square shaped pattern). Apple Support told me to go to my local Apple Store and have a Genius inspect and assess the mura. I made a Genius appointment and brought my MacBook in. The Genius had no problem confirming the mura and said that it was a manufacturer defect that is covered under the Apple warranty. The Genius stated that they would send my MacBook to their "Depot" in Houston, TX for display replacement. I gave my MacBook to the Apple Store on a Wednesday afternoon, and it was returned that Friday. So, Apple shipped my MacBook overnight to Houston by FedEx, the display replaced the next day, and then returned via FedEx the same day of the repair. Super fast and excellent service. I was worried that the Depot repair would scratch or sloppily repair my MacBook, as it is in pristine condition. But my MacBook was returned in equally pristine condition with a new display assembly (the complete display replaced as it is a singular, bonded part).
For those MacBook owners who are curious which screen I had, and what was the replacement, I used the Color Sync app to find out the display information. The defective screen was model "0000A018" and the manufacturer was "00000610". The replacement display was also a model "0000A018" model, and also manufactured by "00000610". The manufacture date code for the replacement is "CCD71000", but I can't seem to find the actual date translation through a Google search. I did remember that the manufacturer date code for the defective screen was different than the replacement, but I did not write it down. My research of manufacturer codes and model #s did not confirm if the screen was made by Samsung or LG. Anyway, the screen looks perfect right now, with no muras detected. As a side note, I take great care of my MacBook to ensure that it is always protected (in a case), and handled carefully. Some online forums stated that Apple Geniuses have told other MacBook Pro Retina owners that their particular muras were caused by pressure on the display (either by pressure on the aluminum exterior, or on the screen). I can say 100% that my mura was not caused by external pressure, nor excessive heat. And from my experience reporting the problem to Apple Support and the Apple Store Genius, I think Apple is conceding that display muras may actually be manufacturer defects, rather than caused by owner mishandling.
So in conclusion, if anyone finds out that their retina display has a mura/muras, Apple should replace the display without question as long as it's in the 1 year warranty period, or 3 year Apple Care period. I'm not sure if Apple would replace the screen out of the warranty period, though. But I think if your MacBook is out of the warranty period, and you have a Genius take a look, they would recommend a "Depot repair". A Depot repair can only be initiated by an Apple Genius, or an AASP, and is a flat rate repair. The flat rate is $280 and will not only replace your display, but will repair and/or replace any parts needed. You may receive a new logic board, keyboard, battery, etc., if the Depot repair technician determines that your MacBook needs it to return it to refurbished condition. According to some other Apple forums, a Depot repair might restore your MacBook to a certified Apple Refurbished condition.
I still have 8 months left on my standard Apple 1 year warranty and will keep an eye out for any new display defects, or any defects on my MacBook. I will update this post if anything turns up. Still don't know if I will buy Apple Care. I never bought it before, and had iMacs, MacBooks, iPhones, iPods, Base Stations, and Express Base Stations since 2006 with no problems. Actually, my late 2008 MacBook had a dead display pixel, which I noticed around 16 months from the purchase date. Even though it was out of the warranty period, I brought it into the SoHo NYC Apple Store and had a Genius look at it. The Genius had the display replaced, via the Depot, with no questions asked. Turn around time was also just around 36 hours, between drop off time and return. Awesome Apple service.