Now this is specifically what I was MOST looking forward too. The Yoda touch-ups!
So far........EXCELLENT!
I'm not really seeing any problem with any of your added mouth movements. They are spot on....in fact they are looking better than what I recall seeing from the PT's CG Yoda.
The only thing I might suggest (as others have) is perhaps a few subtle blinks or eye movements here and there.
I'm also wondering have you tried slightly tweaking his face a bit more (ie very subtle cheek, brow, forehead movement?) I think doing so might help complement the fine work you have already done with the mouth in that the rest of Yoda's face wont stand out as static.
I know you are not going for the full PT CG Yoda look (thankfully, lol) but I think by tweaking the eyes and perhaps a teeny bit more it might all blend together better.
Just something to think about maybe trying.
Awesome work so far AdY.
Happy new Year bTW AdY & everyone!