The response of blades in bladed disks can be represented as a sum of modal contributions from their cantilevered modes and a component induced by the motion of the disk and its interface with the blades. This last contribution referred to here as the disk-induced blade motions is generally considered to be tuned when performing mistuning analysis of bladed disks. Yet, as most of the blade properties, its structural coupling to the disk is likely to be uncertain, for example due to variations in thickness at the blade filet. One thus expects a mistuning of the interface stiffness and mass matrices in particular. The effect of this mistuning on the blade response, which does not appear to have received significant attention, is the focus of the present investigation. A Craig-Bampton methodology is introduced to highlight the disk-blade interface and a mistuning modeling of its stiffness matrix is introduced following the nonparametric modeling method. The analysis with various mistuning models is carried out on a 15-blade impeller finite element model at several resonances. It is found that a small mistuning of the disk-induced blade does not alter notably the mistuned response of the blades.