I think it is a question of testing and seeing.
I used to think that coffee affected by blood pressure only a little - because I tested it at 2 hours (just like I would test my blood glucose)
Then I accidently discovered that the bp rise came 5-10 hours later, not 2 hours. That was a revelation. More careful testing revealed that the bp rise actually lasted 3 days, with the peak around 7 hours after drinking that one cup. I would NEVER have spotted this, if I hadn't been willing to check it out myself. The doc would NEVER have spotted it either - just kept prescribing the pills.
So basically, never assume. Test until you feel you have covered all your bases, and then test again. That way, you will know the full situation.