It's always a possibility, especially in foreign markets where the Model S is very expensive. Here in Canada we have to pay an extra 6.1% NAFTA duty on the Model S (built into the price) on account of the current battery cells being made in Japan. The "foreign" content of that car (cells) makes for less than 50% made in the US so we have to pay an import duty on it.
We're hoping we don't have to pay that, especially on the Model 3, given the cells are made in the US now which could contribute to a better price than most would expect but I haven't been able to get confirmation on this from multiple emails and tweets to Tesla.