I got a somewhat similar email a couple of days ago and I'm a Canadian Amex holder. Maybe I'm confused and it wasn't the same. It was for double Stay and night credits between 15 September and some date in December. Not retroactive, even though I only received the invited 1 month in. Had it been earlier it would have taken us, with planned stays, to 75 nights. Now it seems it will only be 71. I don't see the advantages of Plat 75 being worth a 2 night mattress run but am willing to be educated if wrong.