The Influence of British Accents

I recently met a couple girls from England. It seems a bit out of agreement with my memory but they must have been the first Britons I've ever really talked to. I say that because I've just discovered the strangest thing about conversation with our neighbors from across the Atlantic: I imitate their accent.

It was certainly no intentional thing whatsoever, but the more I spoke with the girls, the more I found myself picking up their accent. I had to continually keep myself in check and consciously bring myself back to an "American accent," however foreign as that may sound to my ears (the phrase, not the dialect).

I was in no way ready to offend their sensibilities nor fuel their preconceptions about rude Americans (I was already informed of the latter by my host friend; no preconceptions on my part) so I was a bit nervous about continued conversation with them. But they actually seemed to take quite a liking to me; perhaps my idiosyncrasy -I assume it is one- went unnoticed. It's been suggested that they may not have noticed because they hear the British inflection all the time in their native country. But I would think that they'd be able to spot a bogus accent that was probably built upon nothing more than hours of watching Monty Python.

With that said, I'm still puzzled over my odd behavior, and am very curious whether it is indeed an idiosyncrasy or not. Do all we Americans, whether because of admiration or derision, carry some innate accent switch that gets toggled whenever we come into contact with Britons?