I've taught adult classes for training and for academic purposes, and I have found that it does not pay for an instructor to bring an ego to class. Any time anyone comes in late or forgets something or didn't do the homework, some instructors take it as a personal slight or a deliberate insult and get an attitude which they proceed to convey to the class. In a group situation this can generate some really bad vibes within the classroom, where hard-working adults are paying money and sometimes risking their own egos and sacrificing their time to better themselves.
I find the best thing to do is move on with the class, and talk with a disruptive person privately after class if warranted. I do not use my position as instructor to belittle or bully class members before their peers.
In this case, where Lynn-z was the only person in the class, it was a great opportunity to make this is personalized one-on-one very special learning event for both of them.DUH!!!
What a shame.