Since you mentioned it is only a spot along the incision line that you noticed some bleeding, it is probably normal. However, be sure to be following your physician's instructions on your post surgical limitation with activity. It is common to feel better and start to do too much too soon but remember your body is still healing from surgery.
I instruct my patients not to lift more than 10 pounds for 6 weeks following abdominoplasty surgery and not to resume sexual activity for 4 weeks.
If you notice signs of infection (fever, warmth to the area, increased redness, yellow or green drainage from the incision, etc) or the areas of bleeding increase, definitely call your physician.