E.R.
If its a good public school then no. Besides, a christian or private school does NOT mean all the kids there are little angels!! There are plenty of 'nice' kids from 'good' families that act bad behind their parents' backs and get into trouble, after all.
But- here is the way I see it: your daughter will have to go through life surrounded by and dealing with all sorts of people, good and bad, of many faiths, of many backgrounds, etc.
It's good that you feel you've given her a strong grounding in your beliefs and strong values- but she has to learn to keep your values, even when others around her may have different beliefs, or not always behave like she does.
I always tell my son " I am not concerned with what so-and-so did or how they acted. I am concerned with YOUR behavior. I expect you to behave the way you've been taught to and use the manners we use in our house no matter who you are with or how they are acting."
I think this applies to your daughter as well. At 4th grade she is getting bigger and needs to be able to deal with more challenging social situations. Just be supportive and aware of what is going on at the school and I'm sure she will be fine.