  We revisit our recent contribution (SIAM J. Math. Analysis, 42 (2010)
2499--2538) and give two simpler proofs of the so-called Haff's law for
granular gases (with non-necessarily constant restitution coefficient). The
first proof is based upon the use of entropy and asserts that Haff's law holds
whenever the initial datum is of finite entropy. The second proof uses only the
moments of the solutions and holds in some weakly inelasticity regime which has
to be clearly defined whenever the restitution coefficient is non-constant
