Possible mucus plug? No picture.

I'm 39 weeks & 4 days. Went to the bathroom this morning & when I went to wipe there was a brown streak on the toilet paper. I kept wiping & it wouldn't stop. It's not thick or sticky like a discharge so that's what worries me. I'm also having light cramps along with this. The baby is still moving & kicking, but I'm afraid. I called my OB, just waiting on a call back. What do you all think?