What does it feel like to lose a mucus plug?

I'm 39 weeks pregnant with my second son, first was a c-section. I've been having light, intermittent contractions for over 24 hours. I went to the bathroom about an hour ago and it felt a little like I was sitting on a balloon that then popped. When I looked at the t.p. it looked like a smear of yellowish brown. And there was a kind of dark brownish clot about the size of a pencil eraser in the toilet. Could this have been a mucus plug?