DD2's labour started off as just having a constant pain in my stomach, I suppose a bit like period pain (I never got it until after DD2 was born and now I have it constantly, thanks ovarian cysts!), by about 5pm (pain started when I got out of bed) I was in tears from frustration and feeling sore and tired and went up to the hospital... 4cm
Take a couple of Panadol and try to rest, if it goes away it's that shirty pre-labour again, if it sticks around you might be in for a long night