Blood Pressure in Pregnancy?

So I am now 28 weeks pregnant with my third and this has by far been the easiest pregnancy up until this point. I have only put on 12 lbs and have been very active with yoga and relaxation breathing. My blood pressure has always run on the low to normal side, but at my appointment a few days ago it was 135/85. I had a few instances of standing too quickly and seeins, and have always been prone to headaches (pregnant or not), but I was convinced it was due to low BP. I can not help but be incredibly nervous now about my BP. At the end of my appointment it was 130/78 and I now have to collect a 24 hour urinalysis along with another BP check on Monday. I did not have any problems in my first two pregnancies and am only 28 years old. Should I be concerned? I can't help but be incredibly anxious about preeclampsia even though they checked my urine for protein and did not say anything. Has anyone else experienced anything like this?