It's still happening. It seems to lag behind about a dozen posts, but as new ones come on, older ones get promoted to "high rated".
Maybe someone is sleep deprived and a little delirious :D
Seems to happen right about when a post is three minutes old. Wonder if there's a crazed uprep script out there? :)
EDIT: Scratch that, just saw it happen to two-minute-old posts. Might be the count then.