Happened to me, too. I must have lost my poker face at that point, because a couple of questions later the interviewer seemed to have noticed that I had lost interest, and asked why. That was a novel enough experience that I was honest, and just said that (a) winning at GH is of zero interest to me, and (b) a corporate culture that actually cares about that is judging their minions by bullshit metrics, causing all the well-known the problems that come from picking proxy measures that don't measure what you actually care doubt.

And if they actually do care about seven day work-weeks being the norm, that's substantially worse.

(Interview ended shortly after I got a muddy reply about how hard it is to measure developer productivity, so they use the metrics they can find, etc. Textbook example of a drunk looking for their keys under the lamp post, which completely reaffirmed my decision.)

Perhaps it was more of a personality test to see how you would answer and not them caring about gaps. Maybe they were seeing if you would come up with a crazy excuse and get defensive. Just a thought.

Edit - It is interesting without knowing intention people say to pass on the employeer. How many interviewers ask stupid questions not realizing they might miss out on a great hire? I think often companies forget that we are interviewing them as well. At any rate I think it's fair to ask in the interviewer why they are asking the question or what is their concern. Especially if the question already made you decide to turn down any offers.

That seems like a reason to pass on them, to be honest.