I can understand this situation. I think I could have done something similar even as I´d know the "most adult" or "wise" thing to do had been to discuss the matter right away. I don´t know if your T has acted like this before but you have the right to claim her complete presence when in session anyhow.

If the call was an emergency call which it seems it could have been, there´s a reason to "forgive" or "excuse" her but only if she takes responsibility for her actions. That could have been done by, as you said, extending your session at the end or offering you a longer session next time.

Even if some might think of actions as slamming doors as a bit childish, I think these actions could be somewhat powerful anyway. Your T surely noticed the large shift in your way to behave when leaving her office. Sometimes people react more to this than just talk and I´m sure she got you were upset.

How are you going to proceed, are you going to call her or just wait until the next session? I feel for you as I know how painful conflicts like this can be, when you don´t know how the other person will act or what he or she thinks.