Rowan - oh good. I'm really quite relieved that you said that. Had you quoted some text from a book or something, I would have been thrown into a quandry, not to mention have set myself on a quest for truth. You think I jest, but nay, I do not!
In any case, I sincerely appreciate your bringing it to my attention, even though it was supposition, because:
some whey proteins apparently DO cause mucus, and
the whole spirulina thing came out of it, which is an even more viable option for the circumstances