Brand new late 2013 15 rMBP annoying screen issue...

Two weeks into ownership wiping my display before closing the lid I noticed that there was one irritating spec that would simply not wipe away with the cloth no matter what i did. Taking a closer look I realized that there was a tiny fissure like anomaly in the screen with a couple of blank white pixels. I then read about pixel explosion but it seems uncommon among the newer late 2013 15 inch retinas. So I took it to the genius bar today and he took a look at it, left me alone while he "inspected" for a few minutes. He came back, took my case off of the computer and informed me they were going to go ahead and replace the screen. The time estimation is 3-5 days... I believe my computer had a Samsung display, will they use another Samsung screen? Whats the difference between Samsung and LG if there is any being used on the late 2013 models? Does this issue occur a lot in the newer 15 inch retinas? How often? Could it occur once again? It wasn't a HUGE deal but once you've seen something on that screen it just can't be unseen :/

Also, is there a limit to how many times I can have anything repaired or looked at on my computer while protected under the 1st year warranty or additional two years with Apple Care like there is on iPhones? Thanks!