Character's ears are going nuts

Not sure what's hapening here, but there are a couple parts of my video where a character's ears just start flipping out for no reason. Any idea what I can do to fix this? 

Here's what the ear mesh looks like:

Here's the ear in its folder:

Most of the time when I use this pupet the ears are fine. They move around a little bit with gravity when the character moves and it looks great, brings him to life. It's just this part and one other moment (so far) where it happens. 

I also have other completely different puppets with the same ear set up that do the same thing occasionally. No idea why!

Other thing: I kind of like the crazy ear effect for some situations, so in addition to fixing this problem I'd also love to know how to get the ears to flap around like that on purpose haha.

Any ideas? Let me know if you need more info/ screenshots/ whatever. Thanks CH gang!