I've created a network discovery rule do scan for web servers with a 60 second delay, enabled it and started the server. It generated a bunch of events, but some event IDs do not match the chronological order. Here's an example:

mysql> SELECT * FROM events LIMIT 4
-> ;
----------------------------------------------------------+

----------------------------------------------------------+

----------------------------------------------------------+
4 rows in set (0.00 sec)

Note, that event 1 and 2 happened after 3 and 4. I haven't changed any discoverer process settings.