In My Humble Opinion ...
 

It's one, or the other, it can't be both.

Or do we need a new definition for an uninterrupted dribble.

How exactly are they mutually exclusive?
A1 pushes the ball towards the floor as a regular dribble, then, he trips over his teammate before he can grab it again and he falls out of bounds. Are you calling him OOB?

More importantly, if the same action (as the OP) occurred in the middle of the court:

A1 trying to dribble around B1 pushes the ball ahead to the left of his defender and goes the other direction around B1. B2 sees the ball and starts to grab it. A1 requests a timeout?

Your call?

Circular Logic ...
 

Good point Adam. Interrupted dribble, because the ball "momentarily gets away from the dribbler", which certainly fits the definition of an interrupted dribble, even though this started out as a "intentional" dribble.

Still, to me, the original post seems like it's not an interrupted dribble.

Maybe we have to use that circular logic, that I really, really hate to use, asking the question, "Would you grant a timeout?", to help us decide whether, or not, its a dribble, or an interrupted dribble? Man, I even hate typing those words.

To me, it's similar to the whole (bogus) concept of the "controlled" tap. IMO, if the players isn't in control enough to grant a TO, he's not a dribbler. It may be a "controlled" interrupted dribble, but it's still interrupted. He voluntarily gave up control in order to avoid a violation; nothing wrong with that, IMO.

As I said...

:(