I would absolutely expect the time to be made up. In fact, if I were the therapist, I'd offer you an extra session at no cost. (I've noticed that my ideas on customer service are not shared by the medical or mental health professions in general, though, so don't hold your breath.)

How did she find about this crisis? Did the client call? Was someone screaming outside? Did she already know about the crisis and just decide to mention it 15 minutes in? And what kind of crisis can be stabilized in 20 minutes?

Yeah, I'd contact her.