Yeah that happened when I saved it... I think it's a transparency problem, because when I drew it I had my brush set on 95% opacity until I noticed it and remedied. Visually it doesn't effect the image, the colour change is so imperceptible... still if it's going to be an issue I'll try restrict it to only the actual colours I used somehow.
EDIT: There, I restricted it to exactly 32, and put the pallette in as well.