I see that your blood pressure has come down significantly with the medication. The initial diagnosis for high blood pressure
may have been an error. Possible. With a major operation at stake, you might have been nervous and perhaps you had "white collar high blood pressure". Sometimes, the effect of certain medications could take a while to wear off from your system. Stop the blood pressure medicine for 2 weeks, recheck your blood pressure for few time, ideally when you wake up first thing in the morning if you have your own machine, otherwise visit the doctor in the morning. 3-4 reading should help you figure out you have high blood pressure or not. Good luck. Certain hospital have machine which you can carry like iPOD to monitor your blood pressure for a week continuously. This can give you a definite answer.