I had something similar, and only noticed the matter shortly before I arrived at the hotel. It wasn't a problem as the hotel could see what I had booked and they didn't know why it had been changed either. Not sure whether the cause is the same as in here: Upgraded but upgraded price too!….be vigilant.

The changed price has also happened to me but the hotels involved were also able to see the original price and changed it back (or instantly refunded in the case where I had already left).