The same was true for Iron Man. He went to the gold armor because the first issue came out with inconsistent coloring.
Aside from the frequent miscolorings, it's also the reason a lot of old comics had bits of color extending beyond the characters.. the overlays were put on carelessly or slipped during production.
Early Marvel often had panels that were monochrome or figures all red or blue. This wasn't an artistic effect, but just an attempt to save time.