Help needed for Telecaster pickup wiring.

I've just opened up the control plate and pickgaurd on my 2004 American standard Telecaster and the wiring seems to be non-standard... The bridge and neck pickup positions on the selector switch sound fine/normal 50hz hum but the middle switch position seems to be cancelling the hum. Has the neck pickup been wired out of phase intentionally to reduce hum in the middle switch position? I'll post my crude wiring diagram here: