MImg Xia had different thoughts in her head when Mr Alex touched her hand to stop her from leaving. Ming Xia did not have anything against Mr Alex, she just didn't like the way he looked at her.
Ming Xia was just being careful because she could tell from the way Mr Alex looked at her that he had something else in his mind about her.
Apart from Ming Xia being careful, she didn't just like Mr Alex. The first time she saw him, she felt angry with him because he had looked at her in a manner she totally disapproved of.
From the first day, Ming Xia had felt irritated by Mr Alex's presence. She just wasn't comfortable around him, hence, she hated his class.
Alex on the other hand was feeling uneasy with what he had just done to Ming Xia. He knew what Ming Xia thought about him but he still wanted to be close. He wanted to make it clear to Ming Xia that he wasn't after what she was thinking and that he'd never force her into any act.