On his way to his dorm, Mark must pick up his medicine at the nurses office. Naturally, Mark is going to take issue with the pills he's being fed, especially when they change. Nurse Lindley isn't too fond of Mark anyway, especially when he nags her about his prescriptions.
That said, she isn't the nicest in the world, and most of the student body would normally avoid forcing her to deal with them. for reasons such as this.