First pregnancy and I'm spotting.

I took myself to the ER the other day when I saw blood, it wasn't that's much, bright red in color. They ran test and told me that I'm in perfect health and that it was too early for them to tell if I could going through a miscarriage. I just came from the rest room and there was blood again, still not a whole lot, bright red. I'm just nervous I guess. How common is this??