If it failed due to a single overload, I'd expect the tube to cripple (buckle in) at the bottom. Imagine what would happen if you took a thin aluminim tube and bent it - the tube would squish and form a hinge, but you'd have a hard time tearing it. If you've got a cheap source of aluminum tube, you could do the experiment yourself.
If you're pole is pre-bent, it should be under tension at the top when you don't have the spin up. With the spin up the top goes into compression. That certainly would cause fatigue sooner or later depending on the magnitude of the stresses. Corrosion could exacerbate that as does a stress concentration point.
Once it has lost a lot of its strength due to fatigue, it'll be a lot more vulnerable to minor mishandling.
