3.3 documentation, Chapter 19, sections 19.1.5, step 3 states: "If a package such as the kernel was updated, you must reboot the host to get the new functionality. If a package such as VDSM or libvirt was updated, you must restart that service to get the new functionality." Need to add - "if sanlock is updated, you should restart sanlockd, libvirtd and vdsmd" Perhaps, it could be simpler to suggest restarting the host.
For reference, the above comment was lifted from this bug: https://bugzilla.redhat.com/show_bug.cgi?id=1080931
As per Allon's suggestion, I have shortened the step to simply read: "Restart the host to ensure all updates are correctly applied."