Item not firing at proper interval

[tighep]

I run an icmppingsec item every 30 seconds out to some of our remote clients (I know that I should tone it down a bit, but we've had issues lately). However, in looking at the database, I see the trigger firing every 1 minute 15 seconds pretty consistently. What would cause the timing to be off by that much?

I don't see anything of interest in the log file, but it does get overwritten fairly quickly.

[vinny]

in fact, frequency of icmpping & icmppingsec are not set within the item interface.
it is set in the zabbix_server.conf :
# Frequency of ICMP pings (item keys 'icmpping' and 'icmppingsec'). Defauls is 60 seconds.
PingerFrequency=60

vinny