  We discuss the possibility of generating adiabatic density perturbations from
spatial fluctuations in the inflaton decay rate which are due to quantum
fluctuations of light moduli fields coupling to the inflaton. We point out that
non-renormalizable operators, which lift the flatness of the moduli potential,
play an important role for the density perturbations. In particular, the
non-renormalizable terms give rise to a considerable damping of the
fluctuations and thereby pose an obstruction to the construction of possible
models.
