Appliance Health has switched to DEGRADED

When discovering some Solaris 10 assets in Ops Center 12c (12.1.3.0.0) I am getting incidents appearing stating that the "Appliance Health has switched to DEGRADED" for the discovered asset. Can anyone shed some light on what this alert is being triggered by?
The assets are agent managed and have a "Current alert status" of "Good". There are no other monitoring alerts for the asset and a Self Diagnosis (OCDoctor run from the BUI) reports no issues:

Ops Center Doctor 4.21UI [OC 12.1.3.2305,SunOS10]
Updating OCDoctor from file /var/tmp/OCDoctor.zip
OK: Found the update file successfully - but no updates were found (current: 4.21, file: 4.21).
Ops Center Doctor 4.21UI [OC 12.1.3.2305,SunOS10] [Read only] [11-Jun-2013 09:28AM NZST]
======= No Enterprise Controller is installed, skipping =============
========= No Proxy Controller is installed, skipping ==============
=============== Checking agent... =====================
OK: Agent requirements are met
OK: No adopt zone error found (CR 6997538)
OK: All agent packages are installed properly
OK: All agent patches are installed properly
OK: Memory usage of agent is fine.
OK: agent version is the latest one (12.1.3.2305)
OK: Best Implementors in NAS Libraries are all unique
OK: Not a Control Domain