Did he see a doctor? If not he should. If he did, what did the doc say?

Did he notice any irregularity of his heart beat? If he did, he could be too low (or high) on potassium and/or salt. These are electrolytes and important in keeping the heart regular.

If he didn't have any irregularities, he could have dropped his heart rate or had a pause....both should be checked out.

BP below 100 will not always cause symptoms of dizziness, etc and rarely causes fainting. BUT, we are all different. My normal barely hits 100-104 and I've been as low as 70/50 with no symptoms at all. Obviously you're different and more sensitive.

Low blood pressure isn't necesarily bad, especially if it's over 90/ as long as you don't FEEL like it's low, dizziness, lightheadedness, etc, you'll be fine with it. But, having said that, it's important that he has this checked out. If his BP is too low, or his heart is too slow or irregular there is a reason for it.....and should be diagnosed and treated.