Ok. I didn't know that "First Seen" is the actual timestamp of an event entering into Zenoss.
During recent issue with one of the devices which resulted in sending a flood of events to Zenoss collector. In Zenoss I could see the signal queue was sporadically increasing during the issue period.
I had to delete the queue a few times. But it will go up again. The issue remained for a few days. When the device was fixed ( so I was told ) , the signal queue continued increasing for a few hours after
the device stopped sending the traps. I suppose the event backlog (somewhere ?) existed. Looking at the Events in UI, I could see the events timestamp was just few mins and not hours. This made
me think that the "First seen" might not be the actual one but rather when it was when queued in the pipeline?
Thanks