It could be a couple things.
1) There is less and less room in your abdomen and the baby could be putting pressure on your intestines so that there is less room for it to accumulate.
2) When left to nature (I mean instead of induction before labor naturally commences) the body usually does a sort of detox and purge. Many women have this happen within a couple days of labor, others it starts a couple weeks before labor.
3) You could have a bit of a stomach bug that is affecting digestion some, but not enough to send you running to the pot or make you puke. You could mention it to your doc/midwife at your next meeting, but I'm guessing it's not anything to worry about.
Effacement, dilation, and station have almost nothing to to do with how soon you will go into labor, so don't let that worry you. They can affect how fast labor will be once it starts, but not when it will start. It's really safer not to have cervical exams done at all, they don't tell you anything you need to know and they can introduce a lot of foreign bacteria into the environment :(
And yes, as a PP mentioned, most women push out at least some poo during the second stage of labor as they push the baby out. Many women don't realize they've done it, especially if they have any sort of pain drugs so they can't feel it.
Good Luck! :)