Sorry, I don't see any problem with the colours being too vivid. I think they're great.
Just an afterthought. When I first got my new paints and painted a turtle, the colour's vividness surprised me. I quite liked it actually. It was said to me that it wasn't a TRUE watercolour. Watercolour should not be that bright and intense. Personally I take exception to that remark. If its painted with watercolour, it IS watercolour.
whew...sure glad I got that out of my system!