Once, at primary school, I somehow got a bit confused and ended up wandering out of the classroom at about 2pm and fetching my bag and putting on my coat and generally acting like it was home time. I then suddenly realised it wasn't home time, and had to take my coat off and try to sneak back into the classroom without anyone asking me where I'd been.
I felt a bit like that when I left work today and it wasn't remotely dark. I actually checked my watch to make sure it was five o'clock!