“It could just be a fun nod, but I think it thematically makes sense, too.
In this particular episode of The Office, most of the attendees at Pam’s art show turn their noses up at her work, finding it boring and unsophisticated. Even her own partner is uninvested. She’s feeling dejected. That is until Michael Scott shows up and appreciates the SHIT out of her art for exactly what it is on its face.
Meanwhile, the innies find Ricken’s book profound because they don’t have any way to contextualize it in the outside world. They take it completely at face value, just like an ‘unsophisticated’ Michael does with Pam’s art. It means a lot to her.
So I think with this wardrobe choice, we’re seeing Gretchen feel appreciated by Innie Dylan in a way that Outie Dylan doesn’t provide. That on the outside, she may be viewed as plain and boring, with a husband that doesn’t put much effort in, but on the inside, here’s her hardworking husband looking at her like she hung the moon.”