Neither of my older two have done it and I doubt they will now at their ages (7 and 5). It would not surprise me in the least if DS2 does it, it seems like something he would try. He's my troublemaker.
He's trimmed the front a few times because it bugs him. I just trim up the rest and suggest he just tell me if it is bothering him. He has easy hair with a bit of a wave so it invariably looks fine.