Policy Violations not getting updated

I'm running OEM 10.2.0.5 on RHE 5 against an Oracle 10gR2 database.  There are a number of critical and Warning violations for a large number of policies that have been flagged.  In resolving these issues I would expect the OEM to monitor the changes and to see those violations drop off.  For example, I have a policy violation where the listener.ora file had the wrong permissions -- easy fix.  It's been over a week now and the violation for that file still shows a policy violation.

How often does OEM scan the system against the policies that are provided out-of-the-box?  How can I force OEM to recheck the policies against changes that I have made to the system?  And how can I fix the problem at hand which is that OEM doesn't seem to be updating the policy checks on its own?