Dear Friend, Out of my  own experience of so many year I can tell you that many people do get little high blood pressure when they go for blood donation for the first time. It is usually out of anxiety. Still to be on the safer side I suggest you get your morning BP say about 7 AM every day, checked and keep a chart of it. If your morning BP is also high then making some changes to life style and diet will bring down your BP, if those measures do not work only then you may need medicine. So do not worry, I think you will be fine. The normal BP  should be 110/70. Best wishes.