I got this info from a Scott Hahn tape ("Answering Common Objections") I listened to a while ago ago. I had the same reaction. And then I thought, "How come I've never heard this before?" In fact, according to Scott, Cardinal Cajetan used this argument against the Protestants hundreds of years ago. I've also found this argument in Ludwig Ott's "Fundamentals of Catholic Dogma."
It's positively criminal that this information isn't widely known among Catholics, probably because it isn't presented anymore in the seminaries. But now you know, so, spread the word!
Oh that makes so much sense. It sounds just like Scott Hahn. I love that guy. I once heard him speak about the relationship of Mary to the ancient traditions of the royal house of David by making a parallel to the way Solomon treats his mother when she comes to his throne to petition him for a special favor. He treats her with extraordinary dignity -- offering her a seat besides his throne and promising to grant whatever she asks.