I just noticed that you silently updated the AIR SDK 3.1 to 3.1.4880.
Comparing the files you can see 23 files were updated in January 9th, 2012.
The original 3.1 SDK was from November 7th, 2011.
Why don't you include a "what's new" file inside the ZIP?
I suppose this new build is just a bugfix release, but you could still tell what's been fixed.
So, what's the difference between this newer 3.1 SDK (build 4880) and the older 3.1?
Regards,
OMA