[ ...he just. facepalms. mostly just for the Sake of facepalming but also because he's a little incredulous, and he doesn't want tonbo to think he's laughing at him?? swords dumb... ]

You said you were fine talkin' 'bout things, but the look ya had on yer face—eyes outta focus, stressed eyebrows, stuff like that—is usually code for "I don't wanna talk about it."