On line 947 of zone.cgi (v2.07) the default TTL for a record is hardcoded at 3600s. This should look at the default_zone_record_ttl valued from nictoolclient.conf instead:
my $zone_record = { 'ttl' => $NicToolClient::default_zone_record_ttl };
change committed to subversion. It will appear in the a future release.