i have noticed recently that scrum halves will touch the ball which is at the back of a ruck, let it go, touch it again before picking it up and passing. i thought that once the scrum half's hands were on the ball it was considered out and available for the oppoaition to play it. There have been a few occasions where the ball has actually been moved forwards prior to the pass being made. Is this an attempt to catch opposition forwards offside or not?