Anyone know the reason for AS scheduling an one-off one way only flight from SFO to FLL on Apr 15?

SFO<->FLL is a seasonal route usually on the schedule between December and March. Currently, the last seasonal flight ex-SFO is scheduled for March 12, and the following day (March 13) for ex-FLL.

The April 15 flight date is filed as flight 206, which is not being used by any other current flights. Current SFO/FLL use flight numbers 371 and 374.