From my own experience if you look at a points booking for 5 nights, you will be shown the average for the 5 nights, thats is if the room rate is 10,000 points a night for less than 5 nights, it will show you the rate as 8,000 points a night, totalling 40,000. So you see in the check 10,000 points a night plus one night free.
Of course if you looked up up a booking of say 3 or 4 nights and it said 8,000 points per night then you have a legitimate concern.
If you still have an issue I suggest you telephone Starwood reservations; I have found them very helpful.