That might be braxton hicks. During your last few check at 38 weeks they should have inform baby's head engaged and if cervix has already open up. First time baby would be long to dilate and signs of contractions. However if you are cautious do call hospital and check with them. They may ask you to go labour and under observation otherwise they will ask you to monitor and any other pain to call up again.
I felt the real contraction and i swear it's not comfortable. It's as if you want to poop a very huge one and the poop is hard but, it's difficult to get it out. That's when you are in labour and ready to push. All The Best!