It is good, that your child can speak up, and knows herself.
So I would not treat her as though something is "wrong" with her.
She has her own disposition.
And she knows when she wants alone time.
I teach my kids that. My kids are 5 and 9. They don't have to be playing together all the time. IF they want to just be alone, they say so. And they tell me and/or their sibling.
My kids know themselves very well, and their emotions.
So I see that as a good thing.
They are not followers. They know themselves.
Every child, has different dispositions. But not all kids know themselves or can say what they need. Your daughter can. That is good.
Nurture that in her.
Not all kids, have to be constantly interacting.
Every kid has a different personality.
It is okay.
Your daughter seems fine to me.
My daughter does not like rowdy kids either.
She CHOOSES her friends.
And she chooses well.
I am proud of her.
She knows what makes her tick, and what friends are compatible.
Just like adults, kids click or not, with other kids. Its okay.