HTTPD error logs filling up. Enterprise Manager to blame?

Since upgrading to 13.0 (currently HF3), my HTTPD log has been filling with errors regarding EM auth tokens.

Dec 11 10:12:49 slot1/bigip1 err httpd[23832]: [error] [client 172.16.0.230] Got exception while handling EM auth token request: Invalid Token: Could not decrypt authentication token: Could not RSA decrypt authentication token., referer: http://localhost:8100/shared/device-availability

Dec 11 10:13:14 slot1/bigip1 err httpd[24494]: [error] [client 172.16.0.230] Got exception while handling EM auth token request: Invalid Token: Could not decrypt authentication token: Could not RSA decrypt authentication token., referer: http://localhost:8100/shared/gossip

This is puzzling because we don't have BIGIQ or Enterprise Manager configured. These vCMP guests are pre-production with APM/LTM modules provisioned.

Troubleshooting steps so far have been:

1. Reset device trust
2. Delete and recreate device trust
3. Restart the HTTPD daemon and clear the .gz files that accumulate.

Is anyone else seeing this behavior in their version 13 BIG-IPs?