I've been getting random period style pains off and on for a week now but, this being my first pregnancy, I'm not sure if they're braxton hicks or what....but I did time them once and they were lasting about two minutes and then going away for about four minutes... I haven't timed since, I think they've just been irregular.:
For me period style pains have always been different than BH contractions. BH usually make your whole tummy feel tight and uncomfy, including the top part of your tummy. And for me, period pains were always lower belly.
That being said, period style pains are also normal--how far along are you?
My BHs are always pain-less and my whole belly just gets tight. With DD, when my real contractions started in labor, they started off feeling like period cramps and got increasingly longer and more painful.
You might mention it to your doctor/midwife and see what they say.