Let me guess, you have a Debit Card on file?
Yes it's just a "pending" charge. IOW's they run your card on the transaction, nothing will get charged.
It depends on your bank on how long it stays on. Most will fall off within a week
Mine takes 3days.
Again, nothing is charged, it's just a billing procedure, it's not uncommon or unique to Barnes and Noble.
If you are wondering, call your bank and ask how long do they hold "pending" transactions before they fall off. Again I would be shocked if it was more than 5 business days.
So yes it's still Free.