Regular contractions that stopped?

38 weeks and last night for the first time, I felt contractions. Light period like cramps, nothing really painful but definitely felt like period was coming on, along with a little bit of tightening. Baby was super active this whole time so it was a little hard timing but for 2 hours, they were 15-20 minutes apart and lasting 45 seconds. I really thought I was finally going in to labor but I fell asleep and they went away completely. I know irregular contractions are normal but what about regular ones that disappear? Has anyone else had this?