Apple's discussion forums are a good thermometer to see if a particular problem arises in isolation or whether we are really facing something that afflicts a considerable portion of users.
One of them, opened in April 2014, talks about problems connected to the MacBook Pro Retina screen (more precisely about the anti-reflective coating that gets stained or starts to come out of the screen). Until then, the case seemed to be something specific, happening only with a few users, but from time to time the topic has gotten in gear at the time of writing this article, there are already more than 47 thousand views and 300 responses.
Apparently there is no pattern, as this problem occurs under various circumstances (pressing keys and the trackpad on the display when the Mac is closed, using third party cleaning solutions or microfiber cloths, etc.).
Even the company's response is not following a pattern we normally see. Some users who still have their Macs covered by the warranty are reporting that Apple is changing the screen without problems; others received a different answer that this is a cosmetic problem, not covered by the guarantee.
Obviously the case is not restricted to Apple forums, there is also a Facebook group of people with this problem, as well as several reports in forums spread around the world. We'll see if Apple has a say on the case.