Almost perfect but I think, and this might sound like a weird nitpick, the style as far as the teeth goes looks best when they're either sharp or a little crooked and spaced out like in the last frames before it loops. You nail the adventure time style the most then. When Fern's mouth is sort of just a pure white space surrounded by black lines it seems... odd, visually. Uncanny might be a better word. But yeah gorgeous work. The gif is uber fluid.