Quotes from Genghis:
"I think that it's probably nothing more or less than a reflection on the zero reference used for the aircraft's AoA instrument."
Agreed! Unless the a/c is in a bunt manoeuvre...
"I don't think that it's telling you anything meaningful about the aerodynamics of the aircraft on its own."
Yes, and wouldn't it be nice if it was telling the crew something meaningful? Isn't it possible - even with a supercritical wing - to establish a reference that approximates a mean AoA for the whole wing, that would approximate at any speed or AoA?
I don't remember having a similar problem with the AIDS AoA readout on the A320, but perhaps someone current on Airbuses may comment.