Index: includes/date_api_filter_handler.inc
===================================================================
--- includes/date_api_filter_handler.inc	(revision 3250)
+++ includes/date_api_filter_handler.inc	(revision 3251)
@@ -395,7 +395,9 @@
       foreach (array('value', 'min', 'max') as $prefix) {
         $default[$prefix] = $this->default_value($prefix);
       }
-      $form_state['values'][$this->options['expose']['identifier']] = $default;
+      if (isset($this->options['expose']['identifier'])) {
+        $form_state['values'][$this->options['expose']['identifier']] = $default;
+      }
     }
   }