At its annual meeting in Indianapolis, Indiana, on June 18-19, the National Federation of State High School Associations (NFHS) Baseball Rules Committee defined what is a balk and what is not for a high school baseball pitcher.
Rule 6-1-1 was revised to specify when a baseball pitcher can turn his shoulders toward base runners while on the mound. It is now legal for a pitcher to turn his shoulders to check a runner if he is in the set position and in contact with the pitcher’s plate. However, if the pitcher turns his shoulders in the windup position to check a runner, it is a balk. Turning the shoulders after bringing the hands together during or after the stretch is also a balk.
“The use of the shoulder turn while in the set position does not afford the pitcher an advantage, ” said B. Elliot Hopkins, NFHS assistant director and liaison to the NFHS Baseball Rules Committee. “The prohibition of such actually creates a disadvantage.”
I copied this section pertaining to the rule above in case some can't find it. I don't have a current NFHS rule book to confirm that nothing has changed since 2005, but there is no mention in the following years, 2006-2008 rule changes that retracts this rule.