I did not receive anything useful from Dell on this.
After checking more, I don't think the problem is actual events happening on the server being sent as traps. In my case, I believe the issue is that the servers are receiving SNMP queries from some other box. Since I had them configured to send traps to my Openmanage server, they are reporting that the query did not have the right security and nothing else.
Looking at the images above, my example event happened at 12:03, the trap I received is 12:08, I had assumed it was just a delay in reporting, but I think the original event was never sent and the alert is unrelated.
I was able to resolve these spurious alerts by turning off trap forwarding from my servers to the openmanage server. I still get 'system down" alerts but I don't know about any others.