Is my blood pressure high?

I went to the doctor today and my blood pressure was 131/82. I know this isn't really that high, but I heard that anything over 120 is "prehypertension." I'm 22, thin, and fairly athletic. My family doesn't really have a history of high blood pressure. Could it just be that high from nerves? I was pretty anxious about the appointment just because I don't like going to the doctor, even though it wasn't about anything serious. I also take antihistamines for allergies and am not sure if that could affect it. Is my blood pressure something I should be worried about?