He knows he know wasn't your disguise good enough? Ofc HE HAD to suspect your an alien ofc he ALWAYS does You were sitting at your lunch since your not hungry your not eating but OFC Dib thinks your an irken, well your an alien but not the same species as Zim

"Scared of food? Or your just not hungry HUH HUH?!"

He's sitting by your side he says suspicious of you