[zwiteof]

The article's explanation is a bit simplified. It sounds like his explanation is more akin to a body freedom flutter response where the aircraft's short-period mode is coupled to the structural response. What he observed is probably closer to a more classical flutter response with the wing's bending and torsion coupled. A gust hits the wing, which increases the load, this increases the bending deformation which can also induce torsion causing a twist in the wing. At too high of a speed (the flutter speed), the response is unstable and can quickly become catastrophic. At normal speeds, the oscillation will tend to die out as the restoring force of the structure and the damping from the structure, aerodynamic loads and controls causes the response to die out. Interestingly, you can go past the first flutter speed of an aircraft with a properly designed control system (aeroservoelasticity) meaning you can get away with a lighter (read, more flexible) wing structure.