For those of you with this problem on Cisco UCS blades, just clear the SEL Log on the blade, and the warning will disappear.
To do that, after signing in to the Cisco UCS Manager:
Go to the Equipment tab and expand it
Expand the Chassis subheading
Expand the appropriate Chassis #
Expand Servers
Select the appropriate Server #
With the appropriate Server # highlighted, select the SEL Logs tab along the top
Click on the Clear button at the bottom of the page
I suspect the process will be somewhat similar for those on different hardware platforms;  the SEL Log will be cleared somewhere within your iLo / DRAC / CMC.