This explains it:
From Microsoft:
Dear XXXXX,
We recently learned that some Microsoft online store customers who preordered Microsoft Complete Accident Protection for their Surface 3 were mistakenly charged $99 too soon.
We regret that it appears your recent purchase was among those affected. To remedy the issue, we have begun issuing refunds to customers for the $99 charge. This may take a few days, and you may want to check with your credit card issuer to ensure your card has been properly credited.
Because of this inconvenience, we will be including Microsoft Complete Accident Protection ($99 value) free with your purchase, you will still receive the full benefits of Microsoft Complete Accident Protection for your Surface 3 device. If you have any questions, please call Customer Support at 1-877-696-7786 and one of our agents will be happy to help you.
We truly appreciate your business, and thank you for shopping at Microsoft Store.