I'm new to therapy and I wondered if anyone could share a similar experience, or put a name to what happened to me?

For most of my last session I completely shut down, hands over my ears, just listening to the white noise in my head. Eventually I heard my therapist say the session was over (she repeated it a couple of times) and I came to myself enough to quickly leave.

I found I was hugging myself afterwards and stayed functioning but "blank" for what seemed hours.

I think I know what triggered that state (nowhere near ready to talk about it) and I figure I had a freeze response, but I'm guessing. I'm also interested in why she didn't intervene?

Any insight/experience would be helpful, thanks.