Was the nurse right?

My IV antibiotics were an hour and 40 minutes late today and the nurse's comment was "Medicine is not exact science" - was she right?

Let's look at the definitons of the words in question.
Medicine: The science of diagnosing, treating, or preventing disease and other damage to the body or mind.
Science: The observation, identification, description, experimental investigation, and theoretical explanation of phenomena.
Exact: Strictly and completely in accord with fact; not deviating from truth or reality; Characterized by strict adherence to standards or rules

At first one would say, sure, there are arguments for both, but the more I think about it, the more I see my nurse was actually right.
We like to think medicine is very exact, doctors follow protocols and rules, are very objective, etc., nurses follow exact doctors orders and patient react to the treatment appropriatelly. But the reality is different, as medical staff and patients are 'only' human beings and subjectivity and human error cannot always be avoided.

The comment itself, however, was not given at the right time. Being late with antibiotics has nothing to do with medicine not being exact science and, if it is already not exact, why push the boarders!