Fainting after blood test?

I know it is common to faint after or during a blood test. But I did not get much blood drawn, I am fine with needles. but afterwards I said I felt dizzy so they walked me to a room to lay down but I fainted for about 5 seconds. My guardian said that it probably was not because my blood was drawn since she didn't think they took enough to cause that reaction but I don't know. I'm a very petite person, 4'11 and 84 lb, so I wonder if that caused for me feeling woozy.