The properties of the primordial perturbations seeded during a stage of inflation are determined by the quantum state of the inflaton. This state is usually assumed to be the “vacuum”, since one expects excited states to decay into the state of lowest energy. In the talk I discuss whether this assumption holds in the presence of a short-distance cut-off. I describe the calculation of transition probabilities between excited states and the vacuum, and discuss the implications of the results that I obtain.