I don't think that not having a want or need met by T, whether it's a hug or something else (being friends outside of therapy, for example) is retraumatizing. It may not be pleasant, it may hurt like heck, it may generate lots of things....It may be therapeutic.
My T gently told me no once when I asked. She told me that, if she thought it would be helpful then she would, but she did not think it would be helpful.
Another time, when she was going to have surgery, I asked if I could hug her and she said yes.
So, it is one of those things, part of the process. And I trust her with the process.