Are these contractions?

I'm 39 weeks tomorrow with my first. My doctor appointment was tomorrow to see if i'm dialated but my doctor is out of town so I wont see her until im nearly 40 weeks. 
I have had no pains, no cramps, nothing. Not like they say you will have anyways. But for the past week, or week and a half, my entire belly will go rock hard for anywhere between 1 to 3 minutes. No pain, or tightness when it happens, just a hard belly. 
Are these contractions? Can you have contractions and not feel them? The baby is head down and has been for a while if that means anything.