TAYLOR: This, young lady, is for the first annual Stars Hollow End of Summer Madness Festival.
LORELAI: You finally found a way to fill September, didn’t ya?
The previous season, there was some sort of Harvest Festival in early September, with scenes of happy people bringing sheaves of wheat to the centre of town, and hanging autumn leaf decorations on lamp posts. The season before that, there was a Teen Hayride in mid-September. It seems like September was getting filled with activities already.
Note that after Lorelai finishes talking to Taylor, she takes a wistful look at Luke, working in his diner, to remind us that she and Luke still aren’t speaking to one another.