Hi, I read your thread about the blackouts.
Since it's closed I'm going to post here.
I know TONS of people who get this. I get it myself.
Usually when I've been sitting or laying down too long and then get up too quickly. Or, if I'm tired and moving too fast. I've never had a problem with this, I've always known it as normal. But it may not be the same thing as yours. if you feel uncomfortable with it, go see a doctor.