I'm still a little unsure whether I should be concerned about this, but right now I'm deciding that she seems to enjoy it, is easily distracted from it, and it doesn't seem to bring anxiety for he while she's doing it or if she doesn't do it on any given evening....
So I guess I'm documenting it to hear your thoughts, and maybe to embarass her when she's a little older?
Here's a picture from the same day, in case you have a slower connection and can't download the movie.
And another photo of another interesting habit: leaning backwards on the couch.