Had a similar experience in the railway station in Brighton, England last summer. I was leading a workshop on street photography that I have done for the past 7 years and always started it in Brighton railway station. I was approached by the Transport Police and told that photographs where not allowed because we may have been taking them for use by terrorists. When I pointed out that we were 17 strong and had at least 50,000 of highly visible camera equipment hung about our bodies and unlikely to be terrorists the sergeant was less that understanding.