If it's still sitting on top of the grass in the same orientation as before you addressed the ball, then I would say it hasn't moved.

It is covered in the "Definitions Section" of the rules...

"A ball is deemed to have "moved" if it leaves its position and comes to rest in any other place."

Based on your description the ball had not moved.

Anytime I have a rule question I go online to USGA.org and can always get what I am looking for with clarity. This would apply

18/2 Ball Oscillates During Address

Q.In addressing the ball, a player accidentally causes the ball to oscillate, but it returns to its original position. Has the ball "moved"?

A.No.

If the ball has not moved, no stroke. But if the ball moves when you ground your club or touching the grass, according to rule 18, you would incur a stroke penalty.

OK......18/2 Ball Oscillates During Address...how do you define a ball that may oscillate .25 to .5 of an inch in either direction while staying in the lie consistently?
For me there is a fine line between movement and oscillation...an oscillating ball in the rough has moved correct????

Dr. K

If the ball has not moved from it's original position, NO.

No, the ball has not moved. I remember having the same question in a competition and also remembered that the ruling was no, the ball has not moved.

This exact same situation happened to me twice during the club championship. I called a penalty on myself twice. I later learned these were not penalty strokes but it was too late as the ball never left it's original spot. Thankfully, I had enough cushion to win. I've since boned up on the rules. Wish I knew them better.

Most of your questions regarding rules and interpretations can be addressed by checking out or purchasing a tome titled "Decisions on the Rules of Golf." It gives lots of scenarios and the decisioins arrived at from real world rules questions.

Addendum...at the USGA website, not only do they have the rules online, at the top of the page there is a "decisions" tab, so both the rules and the decisions are on the same page online. Pretty cool.