If they were saying how big your house is at only 1200sqft it's not because that's such a huge building we in the UK can't imagine such big houses, it was almost certainly a specific comment about your personal situation feeling that you didn't need that much space (or they were indeed assholes and being sarcastic, if it is one of the smallest in the town then maybe they did want to tease about that).

Not to say that UK properties aren't smaller on average as not only are we obviously a much smaller country but we also have a greater proportion living in higher population density areas, as less people here are happy to live outside towns/cities than in the US.