YIKES!
I just talked with the other T and she said that she was going to let current T know that I had called.

I did NOT anticipate that! I said that I would prefer to be the one to tell my current T that I had called asking about an appointment, but she said that she didn't want to be a "secret holder".
So now I'm feeling scared and betrayed. I called her as an information-gathering call so that I could better make a decision. And now she is going to tell my T that I'm thinking about leaving him.
This makes me so mad because it would never happen if they didn't know each other. I feel betrayed. NOT a good way to start a new relationship with a new T.