She will be fine.
Most kids are sensitive, and there will be other kids too who like to hug or not.
She will be fine.
She will not get traumatized by the non-huggers or non-affectionate kids.
Just teach her... that some people like to hug, and some don't... and it is nothing personal. Teach her that everyone, is different.
My kids' Preschool Teachers, taught the kids that. And we taught our kids that too, when younger.
We also taught them that, they cannot "make" someone hug them if they don't want to. You can't make or force someone to do what they don't want to do.
She will also learn, that there is a time and a place for hugging. And its okay.
She is young.
But she will learn and be fine.
As she gets older, she will learn social "cues" better. She is young still.
Mallory P. and Sandy L. below have good points.