sa-update has been failing gpg verification

[Michael Cronenworth]

Hello,

I'm using Spamassassin 3.3.2 on Fedora 15. I'm using the distro supplied 
system script and the included automatic cron job to run sa-update every 
night. Any output from sa-update is put into /var/log/sa-update.log. 
Spam filtering and updating has been functioning correctly up until 
three days ago.

For the past three days sa-update has not been able to update. I receive 
this in the sa-update.log:

error: GPG validation failed!
The update downloaded successfully, but the GPG signature verification
failed.
channel: GPG validation failed, channel failed
02-Nov-2011 05:35:21: SpamAssassin: Update available, but download or extract 
failed


Is there any thing I can look at to see what's causing this GPG check to 
fail?

Thanks,
Michael