Trouble in the "Horizons"

Does anyone pay their bills. According to TMZ.com, Trope and Trope filed a claim against the estate of Anna Nicole Smith for approximately 163,000 in unpaid legal bills. I am uncertain if this is normal procedure to have to file a claim against the estate. I thought typically the executor just pays the bills as they come. From my understanding I thought you only filed a claim with court if the executor has not paid the bills or if an executor has not yet been assigned.