My blood pressure is also normally low. I'd say you are not really "LOW", but at the low end of normal. I think you are okay, unless you normally have higher blood pressure. If you were reclining, or sitting for awhile, and quite relaxed, it is probably lower than it would have been a few minutes before. If it is concerning you, though, by all means give the Dr a call. They wouldn't want you to worry.
I have learned that I can keep going long after I can't.