I've just spent 2 days being monitored in hospital for high BP. My highest was mid-140s/mid-90s, which is officially classed as mild hypertension. Because my BMI is raised, I was kept in for obs and am now on beta blockers and extra super careful monitoring for signs of pre-eclampsia.
Your BP does typically drop a bit in the first half of pregnancy. Anything under 140/90 is technically normal. I have been repeatedly told that pre-eclampsia always presents with protein in the urine, so I just have hypertension. But, being high risk, they take it very seriously. PE symptoms they've drilled into me are the 'thunderclap' headache which is at the front of the head, forehead area over the eyes (i.e. not just anywhere), pain at the top right hand side of your bump, kind of under the ribs (where your liver is), seeing flashing lights and sudden-onset swelling of the face, hands or feet. If any of these happen, go to hospital immediately.
I personally would monitor your BP for a day then call triage or your MW for further advice if it persists towards the 140/90 threshold - one highish reading could be an anomaly, whereas more than two 4 hours apart are likely not. If you do this, be prepared for a hospital stay and pack a bag! It's lots of hanging around on an antenatal ward having your BP taken every 4 hours and it's deathly boring. They do this to see if your BP spikes at any particular time, including the middle of the night. The right size of cuff also seems to make a difference, manual or digital - believe me, I've been through them all.
Of course, if you're really worried, this won't help your BP one jot so get some professional advice asap. Hope it all works out for you!