Brown spotting after an abnormally short period. what's this mean?

Abnormal bleeding: You may have some changes in your menstrual cycles that are normal but you are still ovulating. Some women will have some spotting for days after their cycle ends or if they don't ovulate. I would monitor your cycles and see if there are other symptoms as well to see if this is becoming a normal pattern for you. If it becomes a pattern, i would recommend you talk to your doctor about this.