'66 Pro Reverb. The green heater wires between the two power tube sockets are twisted an odd (as opposed to even) number of turns. Since that circuit runs on AC, does that matter? Don't really seem to get any hum from it.
No, they aren't out of phase. The phasing has to do with where they are wired on the tube socket. The power tube heaters are on 2 & 7, so ideally you want the heater wire on pin 2 to go to pin 2 of the next power tube, and the one from pin 7 to go to pin 7 on the next tube.
On some amps this is important, and some it isn't as important. Some tubes have more induced hum issues than others (12AX7 for instance) If you have no issues, then there is no problem with this.