Error in update via yumex, F16

[Joe Zeff]

Every morning I have yumex update my system while I'm cooking breakfast. 
  Today, it failed with this error:

11:28:59 : YUM: error: rpmdbNextIterator: skipping h#   16675 Header V3 
RSA/SHA256 Signature, key ID a82ba4b7: BAD
11:32:02 : YUM: Transaction couldn't start:
11:32:02 : YUM: /usr/sbin/useradd is needed by nscd-2.14.90-24.fc16.9.i686

Checking, /usr/sbin/useradd exists and has the proper permissions:

[joe at khorlia Desktop]$ ls -l /usr/sbin/useradd
-rwxr-x---. 1 root root 101168 Feb 13  2012 /usr/sbin/useradd

I tried running the transaction again, with nscd unchecked, but it was 
re-added as a dependency.  I let it go to see what would happen and so 
far, at least, it seems to be running OK.  Has anybody else seen this, 
or know why it happened?