A single measurement of blood pressure means very little.
It is actually something that needs to be taken very carefully.
You should have been sitting down, not having eaten or drunk caffeine or having exercised for 30minutes before it. You should be relaxed in a quiet, warm environment with no environmental of physical stressors.
The machine should have been calibrated, the cuff size measured to ensure it fits you arm and it needs to be in the right place.
The arm should be supported at heart height.
It should be taken twice with 5 minutes between each reading.
It should be taken at the same time each day - preferably the morning.
Readings should be compared against similar readings taken with the same equipment in the same conditions.
Safe to say, hardly any BP reading meet these standards - it is more common now for GPs to advise people to take regular readings (twice a day for 2 weeks) at home with the same equipment to improve the standard of measurements before they make decisions about prescribing medications.