Facial Expressions when Yous gettin' into it

do you guitarists tend to make contorted facial expressions with the mouth open and drueling when you are playing a complex solo guitar part? I have noticed on film some of the greats doing this, but when I observe classically trained orchestra players I never see them making facial expressions.. is it because a classical trained musician is using another realm of the mind and does not make it obvious they are "gettin' into it", but actually are, we just don't notice? LOL


