mantis99...Although it's not an "obscure" rule, there's no way a novice would likely know it. The rule is this: the cue tip is considered "alive", even on the edge. Touching any part of the tip, including the edge, constitutes a ball-in-hand foul. Your friend may have accidentally rolled the CB with his ferrule, and touched the tip, with the CB.
Scott Lee
www.poolknowledge.com
World standardized rules.. http://www.bca-pool.com/play/tournaments/rules/rls_gen.shtml
3.40 CUE BALL IN HAND FOUL
During cue ball in hand placement, the player may use his hand or any part of his cue (including the tip) to position the cue ball. When placing the cue ball in position, any forward stroke motion of the cue stick contacting the cue ball will be considered a foul if not a legal shot.