It could be you were Upgraded to Gold when MR combined your stays from '06 and those in '07 and together added up to 50 during a 12 month period.

So I would guess if you have say 64 stays in '07 itself and had another 11 stays in Nov or Dec '06 and none this yr in Nov & Dec then you might be surprised and see they give you Plat. If you didnt have the necessary stays in Nov & Dec of '06 to make a total of 75 altogether then be prepared to remain as a Gold.

BTW do you have the MR Premeir CC? where they give you 15 nights credit towards the 75, so 60 nights a year is all that is needed on Pay Stays to be Plat