Sean,
I'm not sure what value you're refering to, not big on ASDM here.
But I would check:
show snmp-server oidlist
And if you're interested in something you can check what it stands for as usual:
http://tools.cisco.com/Support/SNMP/do/SearchOID.do?local=en&step=1
Potentially you could be interested in:
[25] 1.3.6.1.2.1.2.2.1.14. ifInErrors
[30] 1.3.6.1.2.1.2.2.1.20. ifOutErrors
But that's just interface level.
If I'm correct about my feeling - this particular counter comes from threat detection feature (which is AFAIR not yet monitored by SNMP)
Marcin