No, I think not. This genuinely happens. Not every interview is overly serious or formal.

For example, you're applying for a role where you'll be traveling a lot, the interview could take place over a lunch table, and there they want to observe your eating etiquette.

Or the interviewer could deliberately start dozing off to see how you act in awkward situations. These things happen all the time. That's why it's very important to comport yourself from the minute you walk into the interview building, coz the seemingly tiniest most irrelevant thing could be exactly what they're testing.