I have a friend who grew up in Australia, who's from a state capital while I'm from the country, and he once said that I sounded "more Australian" on the phone to my family than I do while taking to cosmopolitan Australians. I think a lot of us subconsciously suppress our accents and vocabulary when we're not around the exact dialect we grew up with.
I do this too but I think it works a little differently. I would say that we unconsciously tailor the way we talk to align ourselves socially with others.
