Contractions-- Help!

Last night I had about five hours of contractions lasting approximately 45-65 seconds every 4 1/2-6 minutes. They definitely weren't a cake walk but not intolerable either so I decided to wait and see how they progressed before calling L&D. They stayed the same and around 3am I eventually fell asleep. This morning they seem to have gone completely. Is it normal for consistent contractions to go away? Baby is still moving so I'm not too concerned but I was convinced I would be in active labor at the hospital right now.