I hit my 75th Night in the past 12 months on January 15th (it actually only took the prior 10 months) and this would be my first PLAT status. Still showing Gold right now...I'll probably give Marriott two to three weeks to see if they are in fact performing a periodic review of rolling nights producing a PLAT designation online. I'll update this Flyertalk thread either way.

Ironically...when I checked in for Night 74 and 75 on Jan 13th, my account still showed 2 nights left for PLAT and the Renaissance front desk clerk actually mentioned, "congrats...you'll achieve Platinum after this stay". Between that date and the date these two nights actually posted is when Marriott reverted back to showing 75 nights for PLAT status. Confusing yes, but optimistic that the roving computer will catch my many nights in the 2nd half of the year.