Despite the Official Rules stating you can win one weekly prize per calendar month, people have reported not being able to win in week 3 (Feb 7-11) though finishing in the top 100, if they won in either week 1 or 2.

This led to speculation it may be actually a 4 week rolling period since it is a 12 week promotion. At least one person was going to ask PC how they define the months, maybe I missed the reply.