We have this, too, in my 10 week old DS. I think the mucus looks like snot and is stretchy. We also have over supply issues, which I'm block feeding to address. I'm curious if this will end the mucus, too. He has always had these kinds of poops. I know it can mean a virus or allergy, but our doc thought it was normal for him. Hope this helps!
lucky mom to Oliver, 8/6/07, and Finn, 11/28/10, and wife to DH