Out-of-date clients listed, but nothing is out of date

I've been having this issue for a while, but when I check, all of our clients are already up to date. Right now it is showing 8, but later through the day it may change to 2, or some other number. I've been thoroughlly checking through everythign and cannot find out why this is sometimes showing out of date clients.

I attached a screenshot of what I'm seeing. Has anyone else experienced this? I'm running the latest version of SEP.