1. I don't have to finish a level to rate it. This explains why I finished first. Finishing levels can be very time consuming. If I can't figure out what the level is about in a few tries, I mark it with 3s and move on.
2. Any level I've played before may not get played at all before voting. I probably already know how I feel about it.
3. A level ending in ing is scored with great skepticism. If you don't know why...lucky you.
4. I didn't rate all of my own levels a 5...wait, maybe I did. I took care to submit only levels I personally thought were very fun this time around.
Given enough time, I'll go back and perhaps update my votes, but they are good enough if I don't.