Just called dr she said it's the mucus plug passing :)
It could be the beginning of it coming out.
I had something similar happen, called my Dr, to make sure and she asked if we had "done the deed" in the past 24 hours (we had) and she said that it was probably just my body working on getting rid of all the extras (TMI I'm sorry) I have heard that the mucous plug doesn't have to have blood in it but most of the time it does. Maybe call your Dr. and check to be sure.
I wil be 40 weeks on Friday