This happens to me all the time.
I know its just a question, but its getting pretty annoying.
The people that ask this question know that I carry a knife all of the time, so why not change the question to "can you cut this for me?" or "can I use your knife?"
My boss gives me this one at least once a week. "Nick, do you have a knife?"
I look at him with a funny look and he realizes that what he just asked was a dumb question.
Tell me how your guys' experiences are.