Hey, I kinda had the problem. Back at home, whenever the nurse took my blood pressure, I got a high reading for someone my age. I think it was around 130/80 or 90. For an 18 y.o. that's ridiculous I think.
Last semester, I went for a check up at my university's health center, and I got the same reading, BUT, the nurse used a thicker arm wrap thing. And my blood pressure measurement became more normal. (around 115/72 or something if I remember right). The nurse said I had pretty muscular arms so I needed a thicker one.
Well anyway, what I'm trying to say is, maybe you're just too buff, so you might want to try using a thicker BP measurer (I have no idea what they're called).