...you barge into people on the street and no longer realise it's rude
...you happily drink hot water in restaurants and no longer think it's strange
...you consider it normal to go into a shop and go "want ...[points to picture on mobile phone].." with no preamble
Very 'local' symptoms indeed. Here's another: when you ALWAYS walk in the middle of any road, path or lane which is, for example, 5 feet wide. You never ever think in that way you would ALWAYS leave less than 2.5 feet for anyone to pass on your left or on your right. You never ever think if you walk by the left or by the right, you would always leave 3 or 4 feet for people to pass, on either side. Not that you've forgotten all about arithmetics. You've gone 'local'!