The hAPac2 is located at a Client site. The SSID being utilized is unique. In searching the forum I observed that lots of people are complaining about the same issue with other MikroTik wireless models and a few suggestions. I will try some of the suggestions and hope that some of those will fix the problem.
OK I solved the issue by adding the MAC Addy to the Wireless ACL to disallow further communications from the UNKNOWN Source – this effectively stopped the log entries.
FYI, the wireless debug was a big help in coming to this resolution.