When I had my first I was having cramping often during the last month or 2 of my pregnancy, tightening of the abdomen as well. I thought I was going into labor 3 times, and still had to be induced (a week late). So, I would say this is normal, Braxton Hicks contractions, more or less. If the pains start becoming more consistent (depending on how far apart and persistent they are) or you get worried, just call the doctor. They'll let you know if you should come in or not.