I've got a normal whose belly is unmistakeably yellow. It probably doesn't mean anything, but I'm definitley throwing her into some pastel projects once she's old enough. She was from a pastel clutch and has a yellowish/orange hue to her. I love her head marker too!
http://i157.photobucket.com/albums/t...Isis/013-4.jpg
http://i157.photobucket.com/albums/t...s/IMG_0581.jpg
Her next to my pos het clown for comparison. (he's really dark, but you get the idea)
http://i157.photobucket.com/albums/t...IMG_0578-1.jpg