I had decided to do the profile image update. I notice afterwards that the Image profile in Vcenter still listed the original GA 5.1 build. Doing an image compliance check I can see why:
Profile Validation Result
Compliant: false
Host Image Profile: (Updated) ESXi-5.1.0-799733-standard
VIBs in Host Image Profile Only: VMware_bootbank_vmware-fdm_5.1.0-799731
Validation Profile: ESXi-5.1.0-20130402001-standard
VIBs in Validation Profile Only:
Is there some vib missing? This particular host was a clean build from 5.1,,and has had all the previousl patches applied before U1.