Running FBv1.53 db.

One of my tables has an after insert trigger that contains a POST_EVENT.

Running on the same server as my database is an NT service that wakes
up in response to the event (I'm using IBO v4.3Aa) and retrieves all
the recent rows. Each row contains a timestamp and I ask for all rows
added in the last 5 minutes.

The problem: Sometimes, when I respond to the event the most recent
row is not returned even though I know it must have been added in
order to post the event. I've checked my code + logic and cannot find
anything wrong, so the only thing I can think of is that my service is
responding before FB has time to fully write/index/? the record. I
think this is unlikely, but I cannot think of anything else.

Is that remotely possible? My server is a dual opteron,(FB
affinity=1) if that makes any difference to the timing aspects.

Thanks

David