I was just browsing through the top user page and might have spotted an error. See e.g. Tarun with 15.9k reps on the quarterly page.
If i am not mistaken, the quarter just started, so the monthly reps should equal the quarter reps.
For some users the monthly reps equal the quarterly reps, see akrun or Gordon Linoff.
Concerning rene´s comment, that quarter "is quarter", but month could be "last 30 days". That is a good hint, but that would not explain the following stats.
Tarun - Monthly: 351; Quarterly: 15.9k
Akrun - Monthly: 4035 Quarterly: 4035