My boss likes to make passive aggressive personal statements/discouraging remarks/gross overgeneralizations about me/my behavior (and other coworkers but mainly me). For example, I had to make an appointment to have a home inspection to buy my house, which had to happen within three days. I was able to get an appointment for two days away (got the appointment Wednesday afternoon for Friday afternoon). I emailed boss and asked for the time off as I had worked major overtime for a special event. As it was within the same week, it would be flex time and I wouldn't have to accrue comp time. Her response was that I must have been planning that appointment for some time and should have planned my time better. If I had responded with "well, that's an interesting assumption", does that become unprofessional or even insubordinate?
Does your answer change with the knowledge that my boss will see it as insubordinate regardless? Should I use it in that case?