In fact, in a way you're lucky. At the end of my pregnancy, my normally low blood pressure went to 140 / 90, and the doctors were on the verge of inducing me. At least having it be a little bit low at 21 weeks suggests you won't have to face that problem.
My blood pressure is always on the lower end and has remained that way during this entire pregnancy so far - was 90/60 until 34 weeks and now is 90/70. My doctor is not concerned at all. I remember reading that it is common at some point in pregnancy (I believe the first trimester) for the blood pressure to lower a bit. As karenDiane mentioned, 95/65 is not dangerously low - more on the lower end of average. I think it is very healthy blood pressure.
I don't know for certain, but there is someone on the Aug. 2010 board that has low BP and her Dr. doesn't seem concerned. 95/65 isn't dangerously low. Mine was averaging about 110/70 until the 3rd trimester.