My big female used to wag her tail when feeding.
She looked just like a cat, when you dropped the mouse in, she'd start this slow back and forth, back and forth with her tail, like a cat about to pounce.
When she struck, it would stop, only to start all over again with the next mouse.
It might be a different kind of wagging that what you guys are talking about, but she did it every feeding.
Gale