Yeah, he could be reading it the same as someone looking them straight in the face, judgmentally communicating “are you being dumb?”, when it could mean any number of things - like contemplating pensively or not knowing what to say.

The younger generation has had trouble with others watching and judging them in a lot of aspects in life - not just from real life interactions with the older gen, but also things like the constant barrage of being forcefully compared with peers on digital platforms that are incentivized to do so. It can manifest in a lot of aspects in interactions that leave them always feeling inadequate. Acting on that mindset, that could be how “…” can become a negative interaction instead of neutral.

More communication with you about it would probably help him untangle those signals, and learn to relax about it a little, though.