I had the same thing come up - River Belle Terrace Premium Dining Package for Friday May 31st at 5:15 pm. I didn't book it because:
1. I would have had to cancel our 5:30 Blue Bayou reservation
2. I thought the whole point was that you stayed in your seat until the show, which I thought was at 9? So a 5:15 premium package didn't really make sense to me? Made me think it was an error.