Hello , As you have an history of hypertension, you are prone to having high blood pressure. Now removal of adrenals removes an important hormone aldosterone , which is an important reason for salt retention and hypertension. So your pressure naturally went down and you did not need hypertension pills after surgery. But because of your natural tendency over the period of time there will be built up of factors which will push the blood pressure up , resulting in pre surgery like status . So keep a tab on your pressure, sos 24 Hr ambulatory noodles pressure monitoring and consider starting anti hypertensive medication if reading persistently high