Here’s an example of the changing color of the walls from the Blu-ray (uncorrected). This sequence has some horrible color smearing that seems to be on every version of the film from 77 onward, but it’s also clear evidence of the wall sections being painted different colors:
The wall on the left has about ten points more green than the one directly beside it, and neither are gray according to the blu-ray.
JEDIT: Yes, Mike has also said that the walls were painted different colors - see his discussion about the wall sections abutting the droid alcove across from the Falcon, which was intended as a more neutral gray.
The Bluray is so messed up, it has so many random colors just put in that scene for no apparent reason. I guess they could paint it, but I don’t know why they would, but I’m not counting it out. If you look at that scene, the ceiling already has lights in there, and that by itself would change the coloring, but if there were people from the crew that said there were different paint colors, than they would know.
Here is a shot, showing the ceiling lights and the different “paint” color, if they did indeed painted there, and you can see that it’s a different shade of…green. However, even if true, and I shouldn’t doubt that it is, surely, the Bluray cannot be taken as any sort of decent source to go by…IMHO:
