It was more like a bunch of little things. Harry would pick at his plate more than he would actually eat anything, and would often wait until everyone else had started eating before he would get any food. He would jump when he heard a loud noise, like a slamming door, or someone dropping a book, and he would flinch if someone started shouting or someone moved too fast around him. He would actively avoid touch and tense up if someone initiated touch. On top of all of that, he was too small. Honestly, Harry could be mistaken for a first or second year, instead of the fourth year he was.