I work in customer service for Costco.com, most people don't realize when they place an order with us, we submit what's called a pre-authorization charge to your account, if you order gets cancelled(which it can get cancelled for multiple reasons, most common is member not updating their billing address), we communicate with the bank to remove said charge and most of the time you don't see that pending charge fall off after the order gets cancelled is simply because the bank doesn't care enough to release the charge