Not really bugged, but this is obnoxious for sure. I found that she tends to dance more during the panthers swarms, not sure why (possibly adjusting position relative to other mobs, similiar to how you will have large groups of mobs spread out in a semi-circle around you when tanking 20+ of them). I made it a point to give my raid a heads up when she started fidgeting so we didn't mess up on Sonic Screech.
And is she bugged? She seems to keep on moving ALOT even though I'm not moving. It's annoying as hell.