I'm the same; I'm always extremely early. My flatmates, for the most part, are those that will try to turn up on time, but don't really care if they're late, and I was starting to slack off on the whole early thing. Until some time recently (I don't actually remember what it was) I left at a time that would probably get me there on time instead of being early, and circumstances happened, and I ended up late. Felt horrible, and now I'm back to arriving at things really early. Hugely preferable.
I have a friend whose last name is Leat. Everyone jokes that it's an anagram for late because she is rarely on time and often quite late. Makes me wonder if her name contributed to this. When young, she no doubt heard people make this joke to her older siblings and parents and felt she had a legacy to live up to. I think being late is a power trip.