huh, that feels different

So today while John & I were eating lunch I started feeling a cramping sensation in my lower abdomen which hung around for a little bit & I could feel my uterus contracting. For the past 5 hours I've been feeling contractions sometimes stronger than others but still noticeable. Sometimes I don't even notice the contraction until I put my hands on my abdomen and can feel the muscles tightening. So far though it has not been painful, just much more frequent that ever before...it is kind of exciting to think this might be it, and viceversa I'm trying not to think about it too much incase it's not yet time.