Strange Observance today

I was walking down the hallway after school when I noticed something outside the window of my former room. Had I, or hopefully anyone else, been in that room; I'd like to think this wouldn't have stayed this way the entire day. The main entrance and flag pole sets outside that set of windows. I looked out, and I noticed the American flag was hanging upside down. The last time I checked, no one in our school were front runners on any protest/picket line, and I know this was an accident on the part of those who raise the flag in the morning. However, what I couldn't understand is, no one noticed it before 3:00? That includes me; you'd think someone would have noticed it. It turns out it was an accident (thankful that no one at our school would purposely do such a thing), and no one entering the building, in the building, or exiting the building throughout the day said anything. I don't know if others noticed and just let it be or not, but I couldn't believe it was like that for seven hours without no one noticing the mistake.