Hehe. Most PBPs get off to strong starts. The energy going in at the outset is normally quite high.
I say this not to be the dead squirrel rotting under the floorboards of your cabin, but to prepare you for when that energy slackens. That slackening does not have to kill the game...but a lot of people tend to get into a mindset where they're comparing the posting rate to those heady first weeks, and feel like the game is dying.
It's normal though. That's just sort of how PBP games go, most of the time.