Technically, bleeding during pregnancy is never considered normal and should always be reported to your OB. If it's just light/spotting, it can wait until your next appointment. If it is a bit heavier, or there are clots and cramping, give them a call.
All that being said, lots of us have experienced bleeding during pregnancy, particularly in first trimester. Statistically it's about 30% of women. Most of the time everything is just fine. Still, best to let your Dr. know about it.