Upon learning that Lorelai and Rory are planning to backpack around Europe and stay in hostels after graduation, Richard and Emily first of all think they are joking, then throw a fit about it as unsafe and reckless.
The only trouble is, Rory already told her grandfather that’s what they were planning in “Kill Me Now”, and he said it was a great idea. And in “Rory’s Dance”, they talked about staying in hostels while having dinner with Emily, and she didn’t say anything. Suddenly it’s a major problem.
I guess you could justify this by saying that they were simply humouring Lorelai and Rory before, and now they are giving their real opinions, or that they didn’t understand before, but they behave as if this is entirely new information, not information they previously ignored or misinterpreted. It feels like a retcon.