The "Holy Month of Ramadan" must be over, they stop killing as the religious fervor recedes. (How do I mark a comment "sarcastic but weirdly truthful"?)
More like the terrorists are blowing their wad in Western Iraq trying to kill Americans before the election. And, the Madhi Army is busy fighting with the Badr.
The terrorists have an ability to surge attacks, but they wear themselves out after several weeks and it takes time to rearm, regroup, and plan the next surge.