I've noticed this since build 509 and I checked up on it and it persists in 655. Ok I'm using PTUX and the Sun Tower Link palette (cset 6.) On the 3rd level palette (cloudy) the 3rd pixel switches on and off from "broken" and "not broken." I say broken because it will change from a dark green to a light peach. It switches when you leave a dmap of that level palette and come back in. Here's a picture showing the correct cset and the wrong cset. 
I have torn apart ZQ in case of some rule or something but nothing is working, the fact that it switches on and off has made me think this is a bug.
EDIT: No bug, missed a quest rule that fixed it. Can be moved.