The fact that the thoughts that started the mental chain of events for her were so silly caused her to question her sanity and ability to be a cop. Survive and if possible stop the bad guy. Officers are not trained in this and hence don't know if they should extend the little finger of the gun hand daintily as they level the Glock at the center of mass of the perpetrator. In reality people are social creatures and learn the basic rules of social intercourse through observation, practice, and instruction from friends and family. Few enough people are involved in shootings.
Shootings are by definition a hairy mess.
There is no real education in terms of what to do and how to act from a social etiquette point of view. Thus there is a real chance that anyone involved in a shooting may commit a faux pas. This may sound silly. That is the point. People try to integrate their world, past experience, and belief's about how things ought to be into everything that they do.