painless contractions?

I'm 40w today & my belly has been tightening all day on & off haven't timed because there's no real consistency but it gets rock hard especially at the top of my uterus. I had a slight burning sensation in my vagina earlier then went off after a few seconds! I hope this is the start of something & heard that some people didn't even realise they were contracting. Any similar stories? They are giving me a sweep at 9am if nothing happens tonight! Fingers crossed I meet my girl soon.