Metoprolol — Increase to Treat Increased Diastolic BP?

My Cardiologist increased my dose of Metoprolol from 12.5 mg to 25 mg. She said she did it to lower my high diastolic blood pressure from 83 to below 80. She diagnosed me with Hypertension based on that one blood pressure reading (of 83 diastolic blood pressure). What do you think? Do I need to get a second opinion?