Error: invalid state transition from Default with TransitionPrepare

[ericingram]

First of all, I love this library, great work!

Can you help me understand why I am getting this error:
invalid state transition from Default with TransitionPrepare

Code looks something like this:

<CSSTransitionGroup transitionAppear={true}>
  {map(value, (option, index) => (
    <FadeInDownBounce key={index}>
      ...
    </FadeInDownBounce>
  ))}
</CSSTransitionGroup>