Banks are closed for Labor Day. No transaction will hit until tomorrow.
For a credit card it depends on the merchant terms on how the item is processed and when they release the file to the processor. The posting can take a couple of business days.
Further, most merchants don't charge the card until the merchandise ships.
it can take a few days for transactions to appear
Credit card transactions can take several days before posting.
I would definitely think it being labour day has something to do with it. It's not the exact same idea, but one Friday I deposited a paycheck into the ATM and it didn't show up until the next monday or tuesday. I'd wait until tomorrow, and if it doesn't show up then I'd speak with the bank or the website. Not to scare you or anything, but was it a reputable website?