I'm guessing the yellowing is a fluke of sorts. Some kind of factory faux paux that I'd hope is at least receiving a little attention. Still though, seeing a fix, any fix, is a positive I think.
I've fixed a number of the Sandtroopers I'd bought more for the rifle than anything back earlier in the year... Now that they're usable troopers, I'm pretty happy with that. Plus it makes the Wave 5 Stormtrooper more appealing to me, though the price still will keep me away I'd guess.