Q. If I sole my putter behind my ball on the green,

before taking my stance,

and my ball moves out of position, what is the penalty?

A. There is no penalty.  Rule 18-2b Ball Moving After Address;

"If a player's ball in play moves after he/she has addressed it (other than as a result of a stroke),

the player is deemed to have moved the ball and incurs a penalty of one stroke.  The ball must be

replaced unless the movement of the ball occurs after the player has begun the stroke or the backward

movement of the club for the stroke and the stroke is made."

Definition:

Addressing the Ball - A player has "addressed the ball" when he/she has taken his/her stance

and has also grounded his/her club, except that in a hazard a player has addressed the ball

when he/she has taken his/her stance.