No, never. Even if they dont know why they are always fed a standard bullshit answer to give to interviewees. More often than not they say its a "new" position or new work or they are expanding their operations. Thats rarely the case. If they were actually expanding such things would be found on internet. Maybe not the nightly news, but the industry in general would sure know about it cuz expansion involves a LOT more than just hiring more people.
If they say its cuz somebody retired thats just filled with all kinds of problems. It may have been forced retirement or layoffs. The guy may have cracked and broken down. It might be a straight up lie and the person just plain quit.
My last job at Tektronix was a combo of the above two issues. They were "restructuring" which turned out to be the old fashioned "fire a buttload of people and everyone thats left do all the work". I was one of the newbs brought in to replace 3 overpriced paychecks. I made one third of what any of them did. So I was basically 9 times the bargain. I also did 9 times the work. They got rid of most of the people by forced early retirement with pensions at a small fraction. They did expand in the sense they made new divisions, but that was to cover the multitude of areas they had shut down.
But no, such a question NEVER makes the interviewer squirm. They always know either the truth, or a well fabricated lie and they always tell a good lie. And theres no way to know for sure until you actually start working.