Leaders not the same in last month

First off I just want to say thank you for this wonderful product. It is exactly what I was looking for.

I have a couple concerns though.
Last month I was watching the leaders before midnight of January. After midnight, the leaders in the last months tab were not the same as the leaders that were in the this months. (They were not in the same order at least)

Why would this be happening?

Also, I noticed that the module shifted to the next month a little before midnight. How can I make sure this is in sync with my server time zone?

Thanks