BlueRose
It's happened to me, too. However, if my reading is on the high side, my doctor always takes it again later in the same visit. The second time around, it always comes down. Perhaps by that point, I'm more relaxed.
Here's another oddity---I get White Coat Syndrome only when it's my internist taking the pressure. If it is a nurse or the GYN, I don't get it. I think that is because I know that if my meds need adjusting, it's the internist who does that. If it's someone else taking the pressure, I tell them that if it seems high, I will make an appointment to see the internist.
Also, since I've adopted a mostly vegan diet and lost some weight, my highest BP readings aren't so high as to cause alarm.
I would let your doctor know that you do feel nervous/anxious before the cuff goes on your arm. Also, tell him/her that you get better readings when you do it at home. If you check it at home, your doctor may ask you to bring in your pressure reader next time you have an appointment. That way, your doctor can check to see it it is properly calibrated.