I've not heard of any problems but have know people being asked to leave their Sgian Dubh with the door man when going into a bar and I wouldn't go anywhere near an airport with so much as a blunt spurtle these days
Depending upon where and when I'm going I'll wear either a Sgian Dubh or a 'Sgian Brew', favouring the later if in the evening or if drink will be flowing.
I do know of a piper being busted while busting on the streets of London for wearing his Dirk but the case was immediately dismissed by the judge.

Rab