C.P.
Little kids are very vocal and if something is going on when she is on the playground someone will here about it. I would not say anything right now except that she is going to have a great time at school. It may scare her if you say anything then it will be tough for her to go. When you pick her up from school always ask her how it went and if she got to play fun games with the other children. There is always some kind of supervision on the playground and they usually don't let the kindergartners out with the older kids. If you let her experience everything brand new then she will adapt as needed. She will go and make friends just fine.