Yeah, it's normal (and very frustrating). I just went thru the same thing: contractions that were strong and painful, and 2 MINUTES APART only to fall asleep and wake up feeling fine. I was sent home from hospital.
When your contractions are about 5 minutes apart for an hour or more, go to hospital (or when your waters break). If you're now a day past due date, I'd go without question at that time.