Latest Australian radar returns show them going thru level 363 about 105 knots too slow to sustain flight. Weather shows they were likely maneuvering to avoid thunderstorms in the area.
Pretty good chance they might of had one of their probes ice up. Read the following account of a Lufthansa A-321 that occurred just last month :
"By Simon Hradecky, created Tuesday, Nov 18th 2014 17:11Z, last updated Sunday, Dec 28th 2014 22:22Z
A Lufthansa Airbus A321-200, registration D-AIDP performing flight LH-1829 from Bilbao,SP (Spain) to Munich (Germany) with 109 people on board, was climbing through FL310 out of Bilbao about 15 minutes into the flight at 07:03Z, when the aircraft on autopilot unexpectedly lowered the nose and entered a descent reaching 4000 fpm rate of descent. The flight crew was able to stop the descent at FL270 and continued the flight at FL270, later climbing to FL280, and landed safely in Munich about 110 minutes after the occurrence.
The French BEA reported in their weekly bulletin that the occurrence was rated a serious incident and is being investigated by Germany's BFU.
The occurrence aircraft remained on the ground in Munich for 75 hours before resuming service on Nov 8th.
The Aviation Herald learned that the loss of altitude had been caused by two angle of attack sensors having frozen in their positions during climb at an angle, that caused the fly by wire protection to assume, the aircraft entered a stall while it climbed through FL310. The Alpha Protection activated forcing the aircraft to pitch down, which could not be corrected even by full back stick input. The crew eventually disconnected the related Air Data Units and was able to recover the aircraft."