Honestly have no idea but maybe your building just started waxing the floors better? A long shot is that the hot/humid weather is affecting the moisture of the floor... maybe it's a conspiracy?
I do find my C&J shoes to be dangerous on marble flooring. The hospitals I work in are waxed REGULARLY and I am guaranteed to slip with my C&J; less slippage occurs with my other shoes (EG, AS, G&G, etc.). In my situation, my guess is the nails used in the heels are the culprit though.
Hint: walk slower indoors...
Well, it sounds like you and I have similar experiences walking on marble floors in C&Js then. I don't have this problem with the other makers I own (AE and Alden).