I agree with JPPR2 and think the monitor your wife has in her shop is faulty as I thought I read that you said your pulse was 50 and that would make you a very athlete not some to worry about his BP.
Anyway a couple of years ago I bought myself a BP monitor (Omron BP786N) and use it quite often. Not long after I bought it I started feeling crappy at work, I was working in Indonesia at the time at an altitude of 2500m and was worried so I went to the Doctor, they tested my BP and it was high, can't remember the numbers. So one doctor wanted to start me on medicine and the other thought it wasn't that bad. So I thought I would check my monitor as it stores the last 50 or more readings (for 2 different users) and then I used Excel to graph the numbers ( which included a week after going to the Docs) and it clearly showed a trend going up to a peak and then down again. That was when I remembered that I had been bitten by something on the golf course. So 1 reading in my mind is useless. By the way the monitor I have takes 3 tests each time and then averages the result to get what is shown on the screen.
As for eating salt I never use it on anything and don't like salty food but salt doesn't have a short term effect it is over the long term that it leads to hardening of the arteries which in turn means higher pressure to get the blood through. Also I have higher BP first thing in the morning after resting than I do in the evening after working which is counter intuitive to me.
So get yourself a good monitor that has not been used and abused by anyone else and keep a watch on your BP.