This past week I hve noticed that I have a hell of alot more CM than usual too!! I was wondering the same thing, if it is a lead up to the plug coming out or something? Its a bit early for me to go into labour but you never know and i have had some contractions on and off over the past week too. I just get one or two a few minutes apart and then they go away untill the next day.
It must be our bodies getting ready for it all I suppose?