(Gilmore Girls fan site)I think it’s Season 3. When Rory first gets to Yale, it appears that each suitemate has her own bedroom. In fact, Lorelai spends the first night with Rory, in a second bed in Rory’s room.
A few episodes later, it appears that Paris and Rory are actually sharing a bedroom. Did I miss something?
Someone else also told me that Lorelai slept on a mattress on the floor (it is consistent with the whole mattress disposal sub-plot), yet we see her on the second bed at bedtime, giggling with Rory.
My season-4 DVD’s are still on loan to my parents. (We didn’t connect up this past weekend.) But now you’ve piqued my curiosity. So I’ll check it out when I can.
-TimK
I could be wrong, i just moved, so i can’t watch the dvd’s either (still in storage), but i think that Paris is in the room with Rory and Lorelei, i think paris is on the phone with that guy from Princeton, and Lorelei’s comes in and gets onto the old Yale mattress which is on the floor, ….that’s the way i remember it anyway….I think that the blonde girl who is always exercising is the one who doesn’t arrive untill a few more episode…but i’m not sure about that.
Get the Flash Player to see this player.
I finally got my season 4 DVDs. And here’s what happens. When Lorelai and Rory first arrive, Paris is not there. Later in the day, she arrives. And in the scene when Loreali and Rory get ready for bed, Paris is in the room on the phone talking to Terrence, her life coach. Anyhow, Lorelai sleeps on the floor on the old mattress, whereas Rory sleeps on the new mattress.
I cut some of the clips a little close. (Sorry about that.) But here in this series of clips, you can see the sequence.
Except where otherwise noted, content on this site 
I don't think it's inconsistent.
That’s in the first few episodes of season 4. Unfortunately, my season 4 DVD’s are currently on loan to my parents. (But at the rate they’re going, they should be done with them within a week or so.
)
Paris didn’t show up at Yale until a week or so after Rory did. And there were two bedrooms for 4 suitemates. So Tana and Janet share a room, and Paris and Rory share the other room. But that first night, Rory’s roommate was just “P.G.” Those of us in the know smirk at what’s coming in the next episode. But when Lorelai stayed with Rory that first night, Lorelai slept on the floor next to Rory’s bed. And Paris hadn’t arrived yet.
When I can, I can double-check this. But I don’t think there’s a plot inconsistency. Not like Kirk changing his name during the first few episodes. Or Lorelai having contacts (episode 101), then wearing glasses (don’t remember the episode, but she looked good), then saying that she doesn’t wear contacts (episode 119).
-TimK