I have a DCG who does this too. She is 20 months now, and she's been doing it since 12 months. I also sense that at home mommy and daddy run to "rescue" her at the slightest whimper, so they have essentially created a very impatient child. She has gotten better though. When she starts saying she is "done" I say "ok, but you still have to wait a few minutes because fun&care isn't ready to clean you up yet".