Unfortunately, this is a modern day reality. I'm Asian and either wear a turban or a bandana and have not yet been hassled when I'm wielding my very dangerous Nikon, but recognise it could happen.
I think these things move with the times and if the current majority of people committing terrorist attacks (whatever their justification without getting into a political or ideological debate), then the people of that ethnicity will be most likely to be targeted.
It was probably true of Irish people in the 80's during the IRA bombing campaigns.
I guess the problem is, the greater the paranoia, the greater the likelihood. Hasn't stopped me taking pics of the London Eye, British Museum or Big Ben / House of Parliament and it won't in the future.