The same for me, nothing consciously enters my mind to affect my mannerisms (or lack thereof). It could be our mirror neurons talking. We imitate our peers whether we like it or not. Of course, facial expressions or other quirks should never be a source of self-consciousness or stress, as they are quite helpful in focusing a pianist's energy. Somehow, a grimace can contain what would otherwise be an extraneous motion of the playing mechanism. Indeed, the sound is what matters. Pete P.S. What's your name again?