I kind of doubt it considering how much he and Steve bicker about Hawaiian stuff. I just bet that in the early days of their relationship he and Rachel were the exact same way about their cultural differences.

I'm a dual-citizen so I understand both meanings of "vest" and either makes sense to me. However, and my preference is writing fanfiction is to be as accurate as possible to the vernacular of whatever nationality the character is in canon. It just seems more realistic that way.