The decay of a small homogeneous perturbation of the temperature of a dilute
granular gas in the steady uniform shear flow state is investigated. Using
kinetic theory based on the inelastic Boltzmann equation, a closed equation for
the decay of the perturbation is derived. The equation involves the generalized
shear viscosity of the gas in the time-dependent shear flow state, and
therefore it predicts relevant rheological effects beyond the quasi-elastic
limit. A good agreement is found when comparing the theory with molecular
dynamics simulation results. Moreover, the Onsager postulate on the regression
of fluctuations is fulfilled
