40 weeks tomorrow-- crazy movement w/ slight pain

My due date is tomorrow. All night long, I have had a very, very active baby girl. She's been doing cartwheels and pushing on my stomach and cervix very hard. So hard that I have to take some deep breaths until she stops. I've had what I believe is one contraction earlier tonight, where my whole stomach tightened up and it lasted for about 20-30 seconds. But no other contractions, no mucus plug, no water breaking. But the painful movements are new-- anyone experience this? And hope that it's a sign of labor?