See if rod will loosen off. Or if it is indeed tightened at all. Who knows what the po did to it. If the relief is flat, there may be no tension holding it in place. If that's the case you should try tightening it 1/4 turn past where first contact is made. It will add a touch of relief to the neck but not affect the current setup that much.
It may be broken, but my belief here is that a nut is going to take a lot of tightening before the rod breaks. It take a real goof to accomplish this but I know they're out there.
Another thought I had is the hole where the end of the rod passes and the adjustment nut is installed may be large enough that the rod slips one way or another enough that it contacts the wood in the channel.
I do find it odd that a neck would pass QC at the factory if the rod is set in in a position that this would ever happen. it's pretty simple task to visually determine if the rod is going to hit the sides of it's channel or the fretboard before closing it up.
