It's also worth noting that Marriott has an undocumented rolling 12 month qualification period: 75 nights in any 12 month period gets you PLT, it doesn't have to be a calendar year.

So, you say you started staying with them 3 months ago (say, June 1 for example's sake), and have 40 nights so far. If you get 35 more by the end of February, then your PLT should be continuous, or close to it. If not, and you drop to GLD, you should be able to get back to PLT by completing the 75th night before June 1 '09, or whatever the anniversary of when your 40 nights started.