Apple will replace Retina displays on eligible models purchased as far back as June 2012 until October 16, 2017, or within three years of the original date of purchase, whichever is longer. The program was extended to provide affected customers with a longer window of time to get their notebook serviced.
While the program has not been publicly announced, MacRumors has confirmed that AppleCare is still handling repairs internally. If you are experiencing this issue, make a Genius Bar appointment or call Apple support.
The Staingate website has photos of MacBook Pro models affected by this issue. "The stains can start as early as 7 months after the purchase. There is no clear pattern as to how it starts: some experience it in small spots around the edge, on other screens it appears in the middle as large patches."
If you notice any spots on your display, we recommend you report the issue to Apple as soon as possible.