Spotty -
86 for a diastolic (bottom number) is still borderline high.
Usually you don't build up a tolerance to blood pressure medications. Sometimes whatever is causing the high blood pressure gets worse, so it can appear that the medication has "lost its effectiveness", but it's really more accurate to say that your condition has changed and you need more medication.
I have very high blood pressure from an unusual condition. However, I've been on the same dose of medication for nearly 7 years, with no change in blood pressure. It still works!
Also, even if you have "white coat" hypertension (your blood pressure goes up in the doctor's office because you feel stressed at the doctor's), that means that stress affects you. So, you should think about all the other times that you experience stress...your blood pressure will go up. Since even moderately elevated blood pressure can affect every organ in your body and place you at increased risk for heart attack, stroke, kidney problems, etc., it's really important to make sure your BP is controlled by whatever means necessary.