It is an appeal play.
Sorry I'm laid up after some minor back surgery and without my normal reference resources, but think of it this way; its no different if the infielder tries to get a runner going back to third on a line drive or that runner from third scores on a fly to the outfield, only to be called out on appeal for leaving early.
Its the same basic play, just executed in a different sequence.
The umpire's forum has some great historical threads on this topic.