--- nagios.module       2010-07-30 00:03:01.000000000 +0200
+++ nagiosNEW.module    2010-09-17 16:22:02.000000000 +0200
@@ -340,6 +340,14 @@ function nagios_check_requirements() {
   $severity = REQUIREMENT_OK;
   foreach ($reqs as $key => $requirement) {
     if (isset($requirement['severity'])) {
+      // Ignore update_core warning if update cache has expired and nagios_cron_duration has not passed by yet
+      if ($key == 'update_core' && $requirement['severity'] == 1 && $requirement['reason'] == -2) {
+        $grace = 60 * variable_get('nagios_cron_duration', 60);
+        $expire = db_result(db_query("SELECT expire FROM {cache_update} WHERE cid = '%s'", 'update_available_releases'));
+        if ($expire && time() < ($expire + $grace)) {
+          continue;
+        }
+      }
       if ($requirement['severity'] > $severity) {
         $severity = $requirement['severity'];
         $desc = $requirement['title'];