SES actually tweeted about using the first reused rocket launch when the first Falcon-9 landed successfully a couple years ago. They've been in price negotiations since then.
After all the refurbishment and testing the SES-10 launch is only at a 10% discount off the normal cost of a falcon9 launch. Presumably that'll go down as soon as their pipeline for refurbishing the rockets gets better.
Even bigger news is the fact that
SpaceX has now taken A SECOND USAF contract from ULA. Previously ULA managed to twist enough arms in the pentagon to keep SpaceX out of the lucrative DOD contracts but this year ULA is having some trouble getting new engines for their Atlas boosters. The engines are russian lol