[It's certainly a universal sign for "things aren't okay", which does the opposite of what Kano intended there. His own efforts seem to go the opposite direction. His hands go out, like he's going to catch either Kano or the tea, but neither one actually spills. Instead he's left staring back at the boy in alarm.

A long silence follows those words.]

...Ooookay, whatever you thought I just said, you might be. But we're going to move past that. Are you okay? I'm sorry, I didn't mean to scare you. I was just asking if you wanted your tea warmed up...? You like you've been here, uh... a while.