moving bones while in "Weight Paint"

I'm working through Wayne's Fundamentals of Rigging.
in "08 Armature Modifier" he is in mode "Weight Paint" and paints the Head and then Ear.L.
At one point (10:20) he wiggles the ear.  I can't figure out how he is doing.
I can do this object mode by selecting the bone and changing the rotation Y axis.  But when he is doing this, the rotation Y axis value doesn't change.
When I try and change the rotation Y axis in "Weight Paint" mode, the mesh rotates while the bones stay in place.  Worse, CTRL-Z doesn't undo it, it undos the last paint operation.  Shifting back to Object mode, the Y rotation says 0.  If I change it slightly with the mouse, the head snaps back into position.
Ideas?