cristoloro

I have a nurse who is generally spoken high of. Patients and families respond well to him. Recently he changed the language on a ventilator as a "joke". He stayed in the room and changed it back once the respiratory therapist entered the room. Nothing happened during the change but the patient's mother complained about the change. I have done service recovery with the mother, but am unsure of disciplinary action. Should he be coached about behavior or should I go forward with formal disciplinary action? As previously stated this is not the normal behavior and he has already taken responsibility for the error and apologized. Thank you for your input in this matter.