The pubDate is set to the servers local time, but the "r" format indicates GMT.
Convert to GMT.
Change Line 190:
integrationElement.AppendChild(CreateTextElement(
integrationElement.OwnerDocument, "pubDate", System.DateTime.Now.ToString("r", CultureInfo.CurrentCulture)));
To:
integrationElement.AppendChild(CreateTextElement(
integrationElement.OwnerDocument, "pubDate", System.DateTime.Now.ToUniversalTime().ToString("r", CultureInfo.CurrentCulture)));