I saw this in the news yesterday. This game Winfall becomes +EV during the rolldown weeks, as some prizes may increase value by 10x. Here is an article about it:
http://www.huffingtonpost.com/2011/0..._n_916972.html
Here are the actual rules:
http://www.masslottery.com/games/lot...h-winfall.html
Similar to sportsbook's counter measures, the MA lottery is cutting limits by limiting to $5000 per day per store in ticket sales.