Tate angrily grumbled, standing next to his mom in the store while she was buying groceries or just straight cigarettes.

You were in the same store because your parents were buying groceries after a few months.

Tate glanced at you before quickly hiding his face.

You went to school with him and he probably didn't want to see a schoolmate anywhere else other than school.

And he didn't want his schoolmate to see him acting like a brat while his mom scolded him and tugged on his ear.