Yep, I've done that.
I tend to think it is a normal part of facing difficult issues.
We like to test the water with a toe, instead of just diving in head first.
It is ok to be nervous, and it is ok to not talk about it again until you are ready.
If you are concerned, you can start your session with T by saying 'I know I mentioned X at the end of last session, but I am not yet ready to go there.' I'm sure T will respect your wishes.
Missboots, be kind to yourself. You took a huge risk saying anything, even at the end of the session, so be proud of yourself for taking that step.
Many

and warm wishes for your meeting with T tomorrow!