Yesterday I finished learning the Remote Herdkeeping skill. In the quest following this the rock suggested, I kid you not, that I should try shaking butterfly milk. He said something in the line of "this might be something you haven't tried".
This comment seems more appropriate for the quest that comes with AK1.
Actually, now I think of it, I think it's mentioned after finishing the "Happy endings for all" (not sure when you get that one). If I remember correctly the rocks says something like, "what are you going to do with all that milk, try shaking it". But I might be wrong...