I had just a similar experience in NYC, in Times Square in front of the NBC building. I was clicking snaps with my DSLR at around 9 in the night, as were a few hundred tourists at that time, a security chap approaches me and tells me that I should immediately stop clicking the NBC building due to security reasons. I pointed out the endless tourists standing all over and doing the same, he just shrugged and said he' doing what the manager has told him and he wants no trouble.
I guess it did'nt help having brown skin and a big Mtha*&%$* camera, but I stopped . Didnt have any such issues anywhere else in NYC so I consider it as an abberation, most people were fantastically nice.