I also had a lump of CM this morning that had streak of brown in it. When I looked at the toilet paper I just though "What the hell?" But I didn't let the worry get in my mind. It was the smallest amount & I have also been straining a little for number 2's (TMI ) so I figure I probably just strained something.
But get it checked if you are concerned. As it was said anxiety is no good for you or bub.