Wow, never thought I'd see a monthly result where I took the top spot--I even made a post to that effect over a year ago:
I will never take the first position, no matter how much merit I distribute.

And I don't think I'll get above #6 unless some merit sources above me drop out.
I know why it happened, though. For as many times as I've made the offer to review members' posts, it was only when I created that thread with rules regarding said offer that my inbox caught fire. I blew through all of my source and earned sMerits in no time (and I was happy to do so).
Next month I'm sure I'll be down the list, however. Theymos hasn't upped my monthly sMerit allocation, so I kind of blew my wad all in one shot. That second part of that last sentence was redundant, sorry.