Grown-ups the world over know that face-palming and yawning are taken as signs of a person's frustration and boredom, whether or not they are the result of it. I'd be insulted in any one-on-one meeting in which the other person did that and never explained or apologized for it. Even if a person actually is bored, when showing the signs of boredom it's still common courtesy to make some acknowledgement to others one way or the other.

The way you've described how obvious and consistent it is though, x123, I'd almost wonder if it's a bit of a passive-aggressive power trip on your therapist's part. At the very least it's inconsiderate. Perhaps a good approach would be to express concern for their health, i.e. "You know you yawn an awful lot during our sessions. A sensitive person could take it that you're bored. Do you get enough sleep?" You might be helping them out, if in fact they are somehow completely oblivious to the fact that consistent yawning and facepalming without apology can be unkind physical expressions.