  We show that an appropriately defined fluctuation-dissipation theorem,
connecting generalized susceptibilities and time correlation functions, is
valid for times shorter than the nucleation time of the metastable state of
Markovian systems satisfying detailed balance. This is done by assuming that
such systems can be described by a superposition of the ground and first
excited states of the master equation. We corroborate our results numerically
for the metastable states of a two-dimensional Ising model.
