I have a 4th grade DD like this. I spoke to the school counselor and she said that at this age, it is common for cliques to have formed this time of year. She said as long as your child seems happy, gets good grades and is otherwise doing well, and has a couple of good friends, not too worry.
I look at it that my DD is not a follower, forms her own opinions, which means she is less likely to have too much mean girl activity directed towards her.