PBL,
Sorry, as I understand it this does not happen. If sidestick is neutral, wing does not come up due to yaw-roll coupling. The FBW control system compensates for the coupling. (This also answers GMDS's question.)
I think it was a gust.
Wrong, according to Airbus FCOM the A320 will "Roll Conventionally when
using
fast or large rudder inputs" (below).
If it had been a gust, the aircraft would have crashed. At the point
where the wing hit ground, there still was no (or very little) roll input.
This picture proves it;
http://www.airliners.net/uf/53688288.../phpOltUWB.jpg
The acf was saved by the laws of physics.
Cheers,
M