I think the post office workers are all on vacation or something, because U.S. mail has been really slow lately. I ordered some very small ziplock bags from an ebay seller on the West Coast, about a week ago. They were sent immediatly, according to the package tracking. The package was delivered to my local post office today, and I should get it tomorrow.

If you don't get it by next week, I'd advise disputing the charge.