Better double check on that. I have been asked exactly that question by
the
ticket agent at check in every time I have flown for the last several
years.
Even before 9/11. This has been standard procedure in the US for a long
time.

It was standard procedure for a long time, before 9/11 and for about 18
months after it. But then the TSA rescinded the requirement entirely. I
imagine that if you are catching a British Airways (or other foreign
carrier) flight, they may still ask this question. Some of the US airlines
may also still be asking, either from force of habit or for some other
reason. But it is no longer mandated that they do so. US Airways, for
example, has deleted these questions from their check-in kiosks.