The rotors. I wouldn't have counted on it, but after checking them for balance - It sure is. 3.0oz out on one rotor and 1.5oz out on the other. This is a manufacturing issue, there is no way aside from removing material from one part of the rotor (or adding material) where it could make up that much difference.
I'm speaking to Rick @ Baer customer service about this issue, I hope to have a decently amicable solution out of this. I'll post a result when I get it.