The only default functionality for restricting events is to make ALL events admin only
Is the message "'Some events on this server may be restricted to you depending on your admin level. Type /restrictedEvents for more info" ?
If so, this is an event restriction I made, bundled with
Event_EnvControl, and I don't know of any other add-ons using it.
It's no cause for worry, the only events it affects are the environment events it's bundled with. Unless, of course, someone else has used it to make more events admin only. In which case, disabling Event_EnvControl won't help you
Here's another thread on the subject
http://forum.blockland.us/index.php?topic=215023.msg6095505#msg6095505