I think that is a completely normal thing in therapy. I tend to switch the subject to something else when I am feeling uncomfortable, but I keep talking.

My therapist says pushing someone to disclose things before they are ready just makes therapy into another trauma...and you are likely never to see the client again because of it. She wants to help me process through the issues, not just have me run away and never be able to deal with them.

If this whole thing bothers you, tell the therapist. They can find a way to make you feel safe enough to open up.