I, too, tend to pick up accents. I think it is an unconscious attempt to blend in with the people around me. I have become very self conscious about it and it actually inhibits my attempts to speak in another language for fear I may sound like I am mocking them. My mother is from the south but I grew up in the midwest, went to college in Massachusetts, etc. Deep down I think I am totally confused. My best friend claims she can guess who I am talking to on the phone by the accent I switch to.

An example: I made a trip to Disney World many years ago and was in a store in the UK pavilion at Epcot. I don't know if this is still the case, but most of the staff was British. It was like I could feel my mouth and tongue rearranging themselves to modify my speech patterns. I asked a question about an item and the clerk said "Oh, are you from England?" I mumbled an embarrased negative in reply and got out fast.

The worse though is when French speakers speak English to me. The accent is just strong enough to make me want to reply with something only slightly less exaggerated than Inspector Clousseau.