"Running-in" new subs

I've just a bought an Infinity Kappa Perfect 12.1 sub and was told by the
guy in the shop that I need to run-it-in. He told me not to push too many
watts through it until it has had about 30 hours of play at moderate volumes
because otherwise I can damage the voice coil. I am heeding his advice but
does anyone know any more about bedding-in a subwoofer?

Thanks