Do I need to call the doctor? TMI

Cara • Expecting our first baby Jan 1st 2016! Married my best friend after 8 years together 10/10/14.
I'm 36+6 and just about 3cm dilated with his head low. I'm not having contractions that are bad or very noticeable. I haven't spotted or anything this whole pregnancy. I've been slowly losing my mucus plug over the last two weeks. This morning I went to the bathroom and the mucus plug was slowly coming out and had brown mixed in with it. Most likely dry blood. Is this normal??