Starwood Preferred Guest - Recent Redemption Experience (Free Bonus Night?)

Last night I redeemed *wood points for a six night stay at the Westin Tokyo. The redemption level calls for 12,000-16,000 points per night. It is for a stay in October, so the site identified the "cost" as 12,000 points per night. However, when I went to reserve the six nights, which should work out to 72,000 points, it came back with 60,000 points for the stay. Clearly, the site calculated 12,000 points times 5 nights and then gave me the sixth night free. Has anyone else had a similar experience lately? Is there some redemption bonus program going on that I am not aware of where you get a free bonus night when you redeem for a certain number of nights?

Fifth Night Free -on category 3-7 properties

Last night I redeemed *wood points for a six night stay at the Westin Tokyo. The redemption level calls for 12,000-16,000 points per night. It is for a stay in October, so the site identified the "cost" as 12,000 points per night. However, when I went to reserve the six nights, which should work out to 72,000 points, it came back with 60,000 points for the stay. Clearly, the site calculated 12,000 points times 5 nights and then gave me the sixth night free. Has anyone else had a similar experience lately? Is there some redemption bonus program going on that I am not aware of where you get a free bonus night when you redeem for a certain number of nights?

Fifth night free (http://www.starwoodhotels.com/preferredguest/starpoints/redeem/free_nights/index.html)

Great. I had no idea. Thanks for the responses.