when does an idea come to being?

I was working with a lady the other day who was great fun and we enjoyed creating some interesting work together. We bounced ideas between us and seemed quite productive.
Later in the day she made a comment that made me think. she said "we make quite a good team, you and I. I come up with the ideas and you develop them"
This suprised me somewhat because I didnt think that she was coming up with "ideas" and nor was i "developing" them. The way I saw the situation was that she was talking about odd things, and I kept finding interesting connections and ideas. She stimulated my thoughts, but i didnt think that she was creating ideas. Interesting!

So if A metions something funny, and B says "Hey! that makes me think of.." is A the ideator and B the developer? or is B the ideator stimulated by a comment of A?

I guess at the end of the day - who cares?! as long as an idea breathed some life for a moment..... but what if B went on to make a million from the idea? Does A have a claim?