(I got this while doing my project--it's on linguistics--go figure)
"Native speakers of a vernacular dialect who have moved away and now speak more standardly often must attempt a kind of balancing act. They may feel constrained to shift to some degree back to the native dialect when visiting with family back home."
OK so I've never experienced that much of a shift. But it is true that everytime I talk to someone in my family I hear a little bit of twang come back in my voice.