I'm pretty sure that's a harmless message, just snmpd being chatty. If it's overwhelming your logs, you could create a feature request at bugs.freenas.org to filter out those log messages. If you do, post the issue number here.
Thanks for replying @dlavigne . I can't see it in the logs. It only appears at console screen. And only on 1 of my servers. Can't tell what's different in the configuration except for the hardware. I agreed with you, it seems harmless. I'll just leave it for now until next maintenance window and give it some more time.