I signed up for that back in the beginning. It said that shipping was free, but the receipt listed a shipping charge. When the book arrives, I will protest the shipping charge if it is still there.
What I am going to say may be irrelevant to your case but my invoice from Elsevier in the U.K. also showed the full price but I was only charged the agreed discount price. It may be that the computer producing the receipt automatically shows a shipping charge which is ignored when billing you.
Mind you it is disconcerting when charges appear on an invoice/receipt even if they aren't billed against you. My heart leaped for a minute