I'd prefer to call it a happy accident. Plain old white?? Who needs it! Besides, technically, white is all the colours of the rainbow together. Presuming that one of those colours is EVER SO SLIGHTLY more apparent than all the others, which is not hard to imagine, would that cause the strange tones picked up by the film? Keep in mind that the human eye posseses arguably the best lens in the world, in part because it discards what would be either confusing, or useless information to the brain. Film probably isn't so picky. ry