Caroline notices and waves him in, because she's almost done, and even if she wasn't, someone stepping in would give her a reason to get off the phone with this particular challenge of a parent.

"Yes, I totally understand. I will be sure to talk with Ms. Tig. I'm sure that she was simply reading a little too much into some teenage angst. Okay. You have a lovely day. Okay. Bye bye."

She then takes a deep breath as she faces him. "Parents. Can't run a school with them, can't get through your day without one of them getting upset over nothing."