Alert when SNMP credentials are no longer valid

Is there a built in feature I am missing to alert when the node is no longer being polled by SNMP?

I have tackled this by alerting when an interface is Unknown (I then double check the parent node) and by a SQL query to check the performance data has been updated in the last 2 polls. 

But wondered if this has been resolved by a new feature (althou I'm not seeing it)