Tethering of monodisperse, chain-end-functionalized polymer from dilute solution to a solid surface shows three regimes of kinetics. This paper presents support for the hypothesis that the experimentally observed third regime is indeed the transition from mushroom to brush and that it occurs in a spatially nonuniform manner. Both time-step snapshots generated by a Monte Carlo simulation of the tethering process and atomic force microscopy images of actual surfaces during the process show that the third regime is characterized by nonuniform surface texture, while the surface texture is uniform prior to and after the third regime.