Issue with EMS ldap credentials

I am constantly seeing the following in the logs every 20 minutes:

- Cannot connect to ldap server redacted.com (redacted.com domain): The supplied credential is invalid.

But when I go to Administration > User Server and test the credentials it comes back as fine.  Everything seems to be working correctly except the log message.  Anyone have any ideas of what is going on?

The system is running FortiClient EMS 6.0.5.182