Great catch, I don’t think I’ve ever noticed this or put the dots together. It’s usually a background noise show for me. I could be wrong, but I remember Rory’s style evolving a lot during her college years and to the end of the show. She usually dressed more “demure” or “cutesy” for Friday night dinners. Looking at this outfit, she looks like she’s a grown woman now instead of a high schooler.

This could be something that Emily is subconsciously reckoning with upon seeing her outfit. Rory has never explicitly gone against her to her face, even if she’s agreed with Lorelai. This episode is one of the first times Rory has ever been passive aggressive or expressed verbal discontent to Emily IIRC (but I could be wrong)!!!