Yes, the other poster is right i would rule out pregnancy...but always be prepared!! The last thing you want is to sit there and wonder and worry if he had semen on his hands...think about what you are saying..if that was the case and pregnacy happen from that...TONS of women would be pregno!
But just because your period is usually normal..don't think its out of the ordinary to be late sometimes (unless you are having sex) . It happens to all women at different points in there life. Some just dont ovulate one month. Stress never helps a period come any quicker though :-/. Take some naps and hot baths, relax and im sure you will see it soon.
It never hurts to smile :-D