Yes you're age, gender, medical condition fit or not has an effect on blood pressure, it is usually best not to let the Systolic number (top one drop below 90 and the diastolic below 40). You're last reading in on the low side but the thing with blood pressure it is constantly changing. For example if you were to run for a bus this would increase it, however if you were to be relaxed on a sunny beach it will come down. Even eating a meal will alter the blood pressure.
The trick is not to worry too much about it, but if you do have what is known as HYPOTENSION
then you should visit the doctor he may be able to help with medication. .