I believe a little bit of spotting is normal during pregnancy - and it is also normal to not have this.

If you have not had cramps like this before (I did throughout my pregnancy with DS and thought nothing of it as it was the uterus growing), you bleed any more, your baby isn't moving over a few hours (try drinking cold water or whatever usually wakes the baby up) then PLEASE feel free to call your doctor or the hospital for some reassurance. If you're stressed it's not worth trying to calm yourself when you're scared.