Could this have anything to do with it?

"If you installed the stable version and have edited your transistions.ini before installing, then you'll find your old ini in /usr/share/hildon-desktop/transistions.ini.precssu. You can either just copy it over the new one and miss out on the new features, or incorporate your changes"

I haven't edited transitions.ini, but I do recall during the install that it asked if I wanted to use the new one, or keep old, and I chose "new"...