occasionally such bleeding can occur due to stress
&strain.&will be controlled in couple of days.Need not worry in that condition.But if it does not stop -you have to be careful.
When was your period this time? was it delayed? If so there are chances of miscarraige Pl. get sonography
done &cosult a gynac.
If it was in time & if the bleeding persists, still you should consult &get internal check up to exclude certain problems.