Well, this sucks:
Guess when Google AppEngine changed their pricing model?
If I leave things as they are, it'll run out every night and still cost me $15 a month. Pretty sucky for everyone. So far I've made a whopping $10 from donations so I'm in the hole.
What's hitting now isn't actually bandwidth anymore - now it's datastore reads. The leaderboard. I don't know if the size of the database has anything to do with it or if it's just number-of-reads. Well, I'll do what we did with Bejeweled Blitz for XBLA - only read the leaderboard if you get a new high score.
In the meantime, if you want to help me cover my costs, donate!