This probably won't be of much help but this has happened to me: The handbrake applied light came on mid journey which had me checking all sorts of possible causes. I was miles from anywhere useful (depths of France) so having established that the handbrake wasn't on and that the brakes were otherwise working normally I ignored it. The "fault" had disappeared the following morning never to return. That said I've had a number of similar transient faults like the passenger window not completely closing when I closed the door - the door microswitch seemed to be dead but returned to life the following day.
All part of Aero 8 ownership I guess unless anyone knows any diferent!

David