called out at first after walk

Question
 Last night my daughter played a senior league softball game and was walked with no outs and a runner on third.
As she came to the first base bag she stepped on the bag and to a step toward second. The home plate umpire walked toward her and said she was OUT! When asked, he said that
"once she made a move toward second, she was committed".
The pitcher was in the circle, but did not have the ball.
She and others had make this same move in high school ball
ALL SEASON and no umpire never called a thing is there something that I missed.

Answer
If the pitch is in possession of the ball, she is allowed to round the base, but once she stops, she must immediately return to the base or proceed to then next base.  If the pitcher does not have the ball, then this rule does not apply, so I'm not sure where the ump got that from.  I am curious as to why the pitcher didn't already have the ball.  The catcher should of immediately returned the ball to the pitcher in this situation.  At any rate, from what you told me, I'd say the ump missed this call.  Please let me know if you have any other questions.

Coach Mike