They didn't forget to send it. They have a machine that sends thousands of statements at a time, automatically. If they forgot to turn on the machine or something like that happened, many statements wouldn't have been sent, and they would know. If it's just one statement that wasn't delivered, that means it was lost in the mail, misdelivered, or stolen from your mailbox.
If you want to see the statement now, most banks have them on their websites.