Do I have to worry about prehypertension?

DEAR DOCTOR K: My doctor says I have prehypertension. If it's "pre," then I don't need to worry about it, right?
DEAR READER: Prehypertension is a blood pressure reading of 120–139/80–89 mm Hg. That's the gray zone between normal blood pressure (below 120/80) and hypertension, or high blood pressure (above 140/90). We know that hypertension is dangerous. It increases your risk of heart disease, stroke, kidney disease and impaired vision.