I believe that it was a piece of the inner honeycomb structure in the tail cone of the engine that departed the engine, and caused some minor damage to the thrust reversing system.
As has been pointed out by a number of posters in this thread, the status messages were just that - status messages - not warnings or instructions to land the plane immediately, and the crew acted accordingly. Also, MCC were well aware of the situation and monitored the aircraft the whole time to a safe landing.
No-one was in any immediate danger, and the crew, together with MCC did a superb job in handling this minor incident in a professional manner.
Enough said..!