RORY: You said we could talk.
LORELAI: Yes, well I thought you meant about make-up or something.
RORY: When have we ever talked about make-up?
LORELAI: Never, that’s why I thought now would be a good time.
In fact the very first conversation Rory and Lorelai had on the show was about make-up, when Rory asked her mother for lip gloss and received more options than she wanted. They talked about it again when Rory was getting ready for her first date with Dean and Lorelai advised her on make-up, and briefly again when they were all getting ready for their double dates. I think it’s safe to presume that Lorelai and Rory talk about make-up a completely normal amount for a mother and teenage daughter.