If you check out some of the films after aiki-budo, you'll see this backward movement. I believe there is a clip on AJ that shows an excellent example of this. There is also a clip of Peter Goldsbury doing an almost exact copy of the same set of techniques on AJ. He also did this at last years expo.
Matsuoka Sensei also uses a lot of backward movement in his freestyle. It looks strange to someone with my background (yoshinkan, we do mostly forward movement) but it seems to work for them.