It may be something, maybe not... I think I just lost a huge gob of mucous plug - with blood no less!
This is SO reassuring because at my 40 week midwife appointment yesterday, we began discussing 'postdate protocol' for what will happen after 42 weeks, and it got me quite discouraged. I didn't see anything like this until active labour with DD!
I'm keeping my fingers crossed that the party may be getting started fairly soon!
...although I have heard stories of plug being lost weeks before anything happened.