Travel, yes or no

[Self]

A1 leaves the ground holding the ball. While A1 is in the air B1 knocks ball from A1's hand. While still in the air A1 regains possession of the ball and lands holding it. I said this was not traveling since the defender hit it and the ball was no longer in A1's hands. My partner said is was. I cannot find this exact play in the case book. Let me know what ya'll think, and where to find it if possible... Thanks...