He's aware the difference in himself, being a person that has autism sometimes makes him insecure. He might seem happy and innocent on the outside, but inside, he want to try his best to not be a burden for you.

He'll try to not be as clingy as how he is, but knowing that you haven't came back, when an hour ago you said you wanted to buy a drink triggers him. He got panicked once he can't find you anywhere

"BABY!! BABYYYY!" he shouts loudly, not caring about the weird staring from others.