I got one too. This one changed the room type from Queen Suite to King standard room. Of course the zinger is the price went from 1500 MXN to 1600 USD. No explanation. This is not a surprise. An apology as they're kicking your derrière is an American thing.
I doubt this is a big loss. If I were going to Mazatlan, I wouldn't normally book this place. I've been told that from among the various Mexican tourist cities, this is probably among the least safe.