Invasion of privacy in a college dorm?

Last time I checked, trespassing is illegal in all 50 states. Since your private dorm cannot in anyway be considered public property, that means the other student was trespassing. If the door was indeed unlocked, than there is no breaking and entering. B and E requires forced entry. In reality, there isn’t much of a crime here, however it should pose a big concern to college staff. I would escalate the situation to the Dean’s office.