Scale out, scale back in. only works once.

I do a scale-out(scale both x and y to 0), change the image, then scale back-in(both x and y to 1)

This works perfectly, but running the same code again just scales the y values and not both.

BUT! it does work perfectly when not using the .start() method at the end of the animation call

thanks for this cool library! love it. just thought I'd share this little bug with you
