I was so confident like you are. Bought it since it launched. No IR was great until it showed up. mine took months.
I think if you force it to show up, then it will.
I have had that on my iPad as well... I constantly used it at max brightness in broad daylight to show documents (static) to clients. The iPad shut off multiple times due to excess heat from sunlight... just to show you how "hard" I drove that little guy.
And it started showing IR... eventually.
I don't think I want to do that to my new rMBP.
I like your statement, it is clear, it is decisive, and it has made it further clear that IR issues do not exist on every LG screen, there are bad bunches, and it all matters which one you get, so cross your fingers and hope for the right screen!!(not necessarily Samsung) because I have heard a lot of dead pixel complaints with samsung screens and I like my screen, no IR and no dead pixels, just what a rMBP should be...perfect
I think some of us here are somewhat... obsessed with the notion that Samsung screens are always better, and they have already built this "prejudice" against LG screens as a result.
So they constantly try to push LG screens to the point that they show slight image retention, and then they condemn the LG screen for it.
I don't deny that there are rMBP with legitimate problems, but I think this obsessive test is bad because it forces the screen to actually show image retention even on a relatively good display.
Myself, personally, I don't show the same image on screen for more than 30 minutes. Perhaps my screen has IR... but my eyes can't perceive it, and my usage does not allow it to happen. Maybe it'll show up if I keep "pressing" the same image on screen for more than an hour... but... that's not realistic at all.
To each their own, I guess, but I'm happy with my rMBP, and I want to tell other owners to enjoy their rMBPs as well.