Abstract: Reheating after inflation describes all the particle physics processes occurring from the decay of the inflaton up to the establishment of thermal equilibrium. Due to the strong model dependence, it is one of the most unknown stages in the history of the universe. It has been argued that SUSY flat directions are naturally excited during inflation, and that they slow down the thermalization of the inflaton decay products by providing a large effective mass to the fields they are coupled to. We discuss a nonperturbative decay channel for the flat directions which has been generally overlooked in the literature. It typically leads to a quick decay of the flat directions, and, consequently, to a suppression of their delaying effect for thermalization.