I saw the same effect when I produced and used baked textures I made in Gamespace. When I got it over to 3DGS, I used a video_depth of 32 and no point lights in WED, since they aren't needed for baked surfaces.

Like I mentioned over in that other thread, it might be banding because of the conversion from 24 bit to 16 bit with level textures. If the engine were to support 24-bit level surfaces then I would think that would go away. Perhaps I'm mistaken. Even so, with normal textures and lightmaps, I still see banding using 32-bit color depth and 24-bit lightmaps(regardless of intensity of light or quantity). That's on top of quantization errors.