It's perfectly normal and you are at a significantly lower stroke
risk. Many health care professionals make the mistake of thinking a BP reading below 100 represents pathology, this is incorrect. BP below 100 is a normal variation and is only ever a problem if you are symptomatic.
If your blood pressure readings are always around this range and you are not symptomatic, then there is nothing to worry about.
Despite your vitriolic criticism, I am sorry to hear about your sister-in law Doubtfire..