Pattern Brush Help

I'm making pattern brushes to make rivers on a map. The pattern consistes of 2 short lines one light blue over one darker blue which has a wider stroke than the top line. I group these and drag them into the brush tool window and I've done this frequently with out issue but I'm getting these weird graphics attached to the lines that I apply the new brush to. Can anyone identify what the white stuff is and how to remove it?

Thanks in advance,

John