LORELAI: I will tell them when I’m ready to tell them. You have to accept that because I’m the mother and you’re the daughter, and in some cultures, that means you have to do what I say.
RORY: If you don’t tell them in two weeks, I will.
For years, Lorelai has been running she and Rory’s lives by making all the decisions for both of them (in fact, she’s been shown to be quite controlling, like Emily). Now Rory is a few months off seventeen, she is starting to make her own opinions heard, especially when it comes to her grandparents. These are the first rumblings of what will eventually be a major rift between mother and daughter.
Rory says she will wait two weeks before telling Richard and Emily, meaning she’s quite happy for them to miss Max and Lorelai’s engagement party. Maybe she’s in no hurry for them to meet Dean again.
The Annotated Gilmore Girls 