It's a reference to it, but that's not where it came from.

Basically, every September, new university students would get access to Usenet for the first time. Veteran Usenet users would teach them how to use the network. They would become the next Vets for the next cycle to teach those next round of newbies. Well in 1992, most ISPs decided to add Usenet to their offerings, so new users were constantly pouring in. It was a "September" that never ended or an Eternal September.