Hit ball twice while in batter's box

[canadaump6]

Had this happen in a kids game a few days ago. Batter hits the ball into fair territory, it dribbles in front of home plate, and then while he is still in the batter's box he tosses his bat and the bat hits the ball. Can't remember if the bat had left his hands or not.

I let the play stand as the batter was in the batter's box when he hit it a second time and as far as I could tell there was no intention to hit the ball a second time. It was more out of inexperience and not knowing what to do with the bat that made him hit the ball, but really there didn't seem to be any intent. I let the play stand, but now I'm thinking that I was wrong and it should have been called a foul ball.