There are two SNMP triggers on different SNMP items. Trigger B is dependent on Trigger A. Escalations are set to be sent immediately.
The situation is as follows:
21-10-2016 11:38:00 - Trigger B is triggered - Escalation is not sent initially, it is sent 22-10-2016 09:58:53 (which is the error behaviour)
21-10-2016 11:38:01 - Trigger A is triggered - Escalation is sent at 21-10-2016 11:38:03
22-10-2016 09:59:02 - Host is unreachable

In log there is an entry at 22-10-2016 09:58:51 that states: "temporarily disabling SNMP agent check on host".
It looks like the escalation of Trigger B was somehow stuck, because the Trigger A was triggered 1 second after and it was sent when the SNMP agent check on that host was disabled.