Didn't race this one, but often read around different races in case I ever do them.
This doesn't sound good...short last year and long this year!
At least the one consolation of being too long is that the result actually counts, and you've actually run a half marathon at least. If it's short it's not a proper result.
Probably doesn't make anyone feel much better 
Garmins often waiver a bit, but 1/2mile is too much for weaving/not taking the shortest course type answers
Edited: 19/02/2012 at 19:25