It's kind of silly, but what the hell. The Chief does it. His omnicomm wallpaper has been the default since day one, it's not really a thing he does. Might as well be a joke from what will certainly be, someday looking back on it, a better time.

They get moving again, daylight burning, and he's already forgotten he made the sign at all when Wash asks about it.

He repeats the gesture again, slower, tracing the little u-curve more clearly. "Smile gesture," he explains, as if it should be a familiar concept. "Yours was different?"

It would have to be, to not be recognized. He's seen several variations on the smile gesture, over the years, but most are sort of like his team's. It's not the most unique of ideas.