I don't know when this change took place, or if it's even official, but I first noticed the odd 1.5 kW USB SWBC station from Florida at this frequency instead of 15555 last week. I wondered for a second if that was a mistake, then forgot about it as I kept tuning. But it's there now, and I assume it has been for a while. (I couldn't find the database at the FCC for shortwave stations.)
Sounds best at 15549.97, just like the old frequency sounded better if you tuned a bit under the nominal value.