Are you in the U.S.? If so, the answer is yes, your T was wrong. Both of the professionals involved need to get your signed consent. (There may be exceptions if they work in the same practice group.) My therapist has done this a number of times. When he wants to talk to someone else about me, he has a standard consent form, and he fills in the person's name he wants to speak to, and I sign it. The person he'll be talking to has to sign it too. My daughter's therapist followed a similar procedure. She wanted to talk to my therapist. She had both me and my daughter sign forms, and my therapist had me sign a form too. They are very careful to do things by the book. If I found out my therapist had talked with some other professional about me and not gotten my signed consent (verbal is not enough), I would probably hit the ceiling. (But I know he would never do that.)

cat_eyes, I'm glad you are no longer seeing someone who can't be bothered to follow standard confidentiality and consenting procedures.