Thus far, it looks like lines that service hipster enclaves like the Lower East Side and parts of Brooklyn are seeing the most action. The F and L lines both traverse the East River, giving potential suitors more time to gin up the courage to approach those fair maidens. “I don’t know if I would call a guy I met on a subway,” said one single 26-year-old woman last week. “But I might.” Can “Sex on the Subway” be far behind?