I caught my little brother doing this. Does this mean he was masturbating?

[Anonymous]

I caught my little brother put his hand to his crotch for too long than just a scratch while he wiggle his legs. He also put a pillow on top of his crotch like he tried to hide it while we are sitting in an airplane. Did he masturbate? If so, what should I do to him? Should I tell him not to make it obvious? It made me feel aroused.

[Anonymous]

What? Ahahahahaha