Many thanks to davidambler for suggesting I call apple, even though I was no longer covered by apple care. I was able to have my display repaired

. I'm not sure what the cause was, but it did almost literally happen overnight, and seemed to become more noticeable each day.
my repair story:
After about an hour on the phone with apple, they granted me a repair based on the fact my apple care had only expired by 10 days.
After getting approval for a repair (not replacement) I went to the apple store and had the unit repaired. The issue is seemingly a new one, as they had no record of at my apple store.
They replaced the LED and the glass and I took it home and saw a few issues: fingerprints on the underside of the glass, dust and 22 "pockmarks" in the glass coating which looked like dead pixels when there is a light background, the LED was fine, but had this strange
issue.
So I took the unit back to the apple store and had them do another repair, this time suggesting how about just give me a new one. No dice. But the repair (LED, logic board, new glass) should be done in 2 days they said, 5 days later I called in and they said the unit was on hold status and they wanted to try one more thing to fix the LED issue and if they couldn't I would get a new display. The next day it was ready, and I assumed it was going to be a new display due to how fast the issue was resolved (overnight). But, it turns out they replaced LED and put the same fingerprinted/pockmarked glass back on.
I pointed out the glass was the same and the new LED they put in had a dead pixel, they replaced the glass, but it had the same pockmarked issue, I suggested maybe another apple store would have glass that wasn't so faulty. So I went to another apple store, had the glass changed, but still there was pockmarks and now lots of dust under the glass, at which point, i gave up (I was beginning to feel like a crazy person) and went home with what I had which was not perfect, but better than what I had before.
I was very happy to have my unit repaired for no charge, but wish that there was some sort of quality control at the apple stores and things like monitors are sent to a factory and refurbished/repaired.