Are diarrhea type cramps without diarrhea a sign of impending labor?

I woke in the middle of the night last night with abdominal cramps that felt just like waves of bad diarrhea cramps. However, I did not have a bowel movement or any diarrhea. I layed down and eventually fell back to sleep and woke up in the morning with the pain gone. I am almost 40 weeks pregnant. Can this be a sign that labor is near?