The /var/log/messages files are filling up with messages similar to these:
Dec 7 15:50:48 hostname snmpd[2621]: Received SNMP packet(s) from UDP: [10.22.1.2]:34665
Dec 7 15:50:48 hostname snmpd[2621]: Received SNMP packet(s) from UDP: [10.22.1.2]:34666
Dec 7 15:50:48 hostname snmpd[2621]: Received SNMP packet(s) from UDP: [10.22.1.2]:34667
Cause
The NET-SNMP sends logs into /var/log/messages every time an SNMP query is sent to this machine.