That's interesting, I don't know why a dog would suddenly revert to a previous behavioral phase after spay surgery.
It's possible, I suppose, that her hormones are still out of whack. Was she in heat, or close to it, when she was spayed? It takes about 6 weeks post-surgery for the hormones to settle down.
I've heard that bitches can have a temporary increase in testosterone right after spaying, which if true, could explain her extra energy and "naughtiness".
How old is she now?