I don't see anything wrong with her putting a "dust ruffle" on your quilt. In fact, the color she used may have enhanced the quilt. If I had a quilt for my bed, I would put a ruffle on it.
My reason and possibly your friends, I cannot put a "bed skirt" Dust Ruffle between my matress and springs.
Don't feel bad! What if she just gave it back like some I've read. Be happy that she is happy with it!