Is it possible that you have a scheduled discovery setup which scans this device, but you have the public string higher in the priority order than the current string?
In the above scenario, SolarWinds would be scanning your device every time that discovery runs and attempting to connect using the public SNMP credentials. When it fails it will move down the list to the next entry until the connection is successful.
This would show an SNMP Failure on your device
This is a good idea! However in this scenario, this is not the case.
It could be other users are running ad-hoc discovery scans, searching through the Solarwinds Events (Discovery Profile *) that turns out to not be the case either.
i had similar issue when i ran the discovery for a set of devices... the string public had higher priority and it was taken first... in 1-2 nodes i could see the device having public as the comm string when i clicked on edit properties..
You may want to re-check this again...
Do you also have Network Topology Mapper? Similar type of discovery happens with it to make maps