Hello,
since you know the exact time of the problem, I would run the two EEM scripts below to capture the debug output, and then review that output, or post it here. In the scripts below, the debug starts at 1:24AM and ends at 1:31AM, since at that time it will most likely not affect any users working.
event manager applet DEBUG_SNMP
event timer cron cron-entry "24 1 * * *"
action 1.0 cli command "enable"
action 2.0 cli command "debug snmp detail"
event manager applet UNDEBUG_SNMP
event timer cron cron-entry "31 1 * * *"
action 1.0 cli command "enable"
action 2.0 cli command "no debug snmp detail"