Blood pressure is simply a measurement at that time. There is a range of normal, but high blood pressure is a known risk factor for cardiovascular disease including heart attack and stroke. From memory, CASA use a limit of something like 140/95 before they want more information to help quantify that risk in an individual. Your 125/88 is OK, but some regular aerobic exercise, less salt, and less alcohol are always good things to help it.
I don't think there is a lower limit of BMI, but if a low BMI is due to an eating disorder, CASA will take an interest due to the psychiatric implications.
Hope that helps.
Cheers