Employee Left Early

I have an employee who left early on Friday without asking if it was ok. She is technical (xray) and I am pretty sure she is still under her old way of working in the hospital which is that xray is her only job. I need to talk to her about this; she is a good, conscientious employee but she is very set in her ways and sometimes resistant to change. I am having trouble with my models, probably because I don’t really think she did it in an “eff you authority” manner. I think it’s just something needing to be clarified.

C Maria left early
T I now need to have an unpleasant conversation, show her who is boss here
F Angry, resentful, tense
A Go to work and rip her one for her action
R Unpleasant, tense, unproductive conversation

C Maria left early
T I need to clarify what is expected so we are on the same page
F Determined, confident in my authority
A Have a meeting to clarify what is expected of Maria after xrays for the day are finished
R Expectations are outlined and communicated in a clear manner