DTW-IAH 7/16/12, DL4926. ExpertFlyer is showing F5, but there are only 4 seats available. I can understand the other way--more seats open than for sale--but less? Two specific questions:

1. If someone buys 5 F seats, where would the 5th person sit? The jump seat? Or is there someone who has a seat in F who would go to Y?

2. Assuming there are at least 5 elites on the flight in Y and assuming no one buys an F seat between now and departure, how many elites will be upgraded? If 4, why only 4 when they're selling 5 seats?