Why does it bother Sal in Chapter 11 when Ben points out that she flinches whenever someone touches her?

From the text:

"It bothered me, what he had said. It occurred to me that my father didn't hug me quite as much any more, and that maybe I was starting to flinch whenever anyone did touch me. I wasn't always like that. Before - before everything went all wrong - we were a hugging family. As I walked along with Ben and Phoebe, I saw a picture in my mind of my mother with her arms around me. I saw another picture of myself when I was three years old. My mother was carrying me on her back up to the barn. My arms were wrapped around her neck and my face was tickled by her hair. Her hair smelled like roses. She licked the skin on my arm and said, 'Um, you're a delicious Salamanca Tree, a most delicious Salamanca Tree.'

"Had I been drawing away from my own mother? Did she have empty spaces left over?"