Why rename many files when few file do trick

(cherry picked from commit eaa4a358e8eb93e15203001d16e868e22aded5c3)

Closes #2465

src/NzbDrone.Core/Notifications/NotificationService.cs

@@ -277,7 +277,7 @@ namespace NzbDrone.Core.Notifications
         {
             // Don't send health check notifications during the start up grace period,
             // once that duration expires they they'll be retested and fired off if necessary.
-            if (message.IsInStartupGraceperiod)
+            if (message.IsInStartupGracePeriod)
             {
                 return;
             }