Quatre knows he didn't need to ask, but there's a certain level of gratification at hearing Trowa's response.

His smile broadens, shifting sideways so that he's facing Trowa on the haybale, left hand lightly gripping Trowa's arm and right resting on Trowa's left leg as he leans in and kisses him.

(It's possible, as the kiss deepens, that his left hand moves to lightly cup Trowa's face, thumb stroking his jaw.)