No alas it cannot mean what you say.
It really DOES mean that you are on medication that is controlling a previously diagnosed hypertension. They would never use the phrase "controlled hypertension" to describe a situation where BP resolves by relaxing for a while during an appointment,..at least not correctly.
It sounds like they may have mixed up your chart or your doctor was doing some interesting drugs when he examined you.
Or else just not listening to you...a shock