One of two things is happening here: either I'm seeing a pattern where there isn't really one, or 's episodes of MLP tend to come with some of the best/craziest facial expressions. It's really noticable when a character's face goes off-model, and maybe it happens more and they slipped my mind, but they seem to occur more when Raven boards an episode. I feel like I ought to have a look at more of the board artists on the show, see if I can pick out particular gestures/poses/angles/etc that seem to be unique to each artist.
Unfortunately, ain't nobody got time for that, (I REALLY should've been working on some work for university instead of this comic) so I'm just gonna go with this for now.