Plaid = Sad?

I haven't seen the beginning of the film but, I've noticed that the main (child) female lead is always wearing plaid. I assumed '90's flannel/grunge fashion until she went home, where her dad is having soup, wearing a plaid shirt. He's moping on the sofa, plaid. When he finally goes to his daughter's game, it's chilly so, he put his plaid coat...over his plaid shirt. LOL!