Well I can see that as well but for sure those are not the number of nights/stays since I reached platinum status early December last year. It seems to be equivalent to the number of stays/nights during the last 365 days (from mid October 2014).

But whatever it shows, I won't re-qualify based on the number of nights but rather (because of the various promotions, Facebook points etc.) based on the number of points. The relevant information can't be found anywhere.