I work at ITA and review puzzle submissions. I can't say what practices were 10 years ago (before we had our first customer!), but I would be shocked if this happened today or even several years ago when I joined. All of us did a puzzle to get an interview and we respect the time and effort it takes.
ITA probably had their first customer by the time, as it was already prominent and a success story in Lisp community. I must be misremembering the exact year.
Anyway, no biggie. The puzzle was among the simpler ones (solving a maze iirc), and I was mailing out tons of job applications at the time - with low expectations for each individual one.