I bet she'll completely change before school starts. I had a 3.5 year old that did that for about a week then back to normal schedules.

If I were you I would just make sure she gives one last push on the toilet. Give her a book and make sure she gets to the end. Maybe a timer... maybe a song she can sing and she's not done on the toilet until the song is done. It sounds like she's not getting it all out on the first go. She may just need to be reminded to slow down.

There are bathrooms in almost all kindergarten class rooms. The kids just go as they need to. At my kids school they were encouraged to not even ask, they were just to go when they felt it.

She'll be fine.