“Ten minutes”

LUKE: I go up there every ten minutes pretending to get something to keep them from doing something we don’t want … I got a good system, it works.
LORELAI: Every ten minutes?
LUKE: Like clockwork …
LORELAI: Ten minutes. Yeah, that’s pretty much the time it took to create Rory. And that included getting dressed and freshening my lipstick.

Luke was originally so concerned about Jess and Rory kissing in the apartment that he laid down the law and said they weren’t even allowed to sit on the sofa at the same time. Now he’s become so relaxed that he’s cool with them lying on the sofa in an embrace, making out for hours. He just checks on them every ten minutes.

Luke’s sudden change of attitude seems to have begun when he started dating Nicole, suggesting that his concern about Jess and Rory being together was at least partly fuelled by an unhappy awareness that he was without a partner, while his teenage nephew had a girlfriend.

Lorelai points out that ten minutes provides ample time to have sex, and says that conceiving Rory took her well under that time. (Yes, this is a slam to Christopher, but to be fair, he was a teenage boy). She doesn’t labour the point, but Luke immediately looks panicked.