  Supersymmetry breaking sectors generically have an approximate global U(1)
$R$-symmetry. Thermal effects tend to restore the $R$-symmetry in the reheated
early universe. We revisit the gravitino generation from the thermal plasma and
we argue that an $R$-symmetric phase suppresses the gaugino masses and thereby
the production of the helicity $\pm 1/2$ gravitino component. For reasonable
values of the hidden sector parameters the gravitino can account for the dark
matter of the universe with a relic abundance characterized by a remarkable
insensitivity to the reheating temperature.
