I developed very high blood pressure in my 30s. After many tests to rule out causes, it has been recorded as idiopathic - no known cause. I was at my lowest weight ever, but still overweight. It was such an insult when I'd been working so hard to get my weight under control for several years preceding. One high reading is no cause for alarm, believe me. Your BP numbers move around quite a bit from day to day. If you had the reading done in the chemist, perhaps pop back in daily for a few days to see what the numbers are? I am currently wearing a 24 hour monitor (getting it off in 2 hours.. and can't tell you how relieved I am - not the best night's sleep I've ever had!) to check whether I can start reducing my medications for high BP. After running high for years even with medication ( higher than your reading most of the time), it seems something has shifted and my new readings are down to 100/60 (from an average of 160/90) and I've experienced dizziness a bit when I stand up. So it's hard to know what might have caused your high-ish reading, but it's definitely worth pursuing and also finding out whether there's any reason behind it. I had a lot of tests including ultrasound of my kidneys to try to figure out what was going on with me, but everything checked out fine.