...and the gas lines might go out during the Apocalypse too.
Might?
I doubt keeping the pipelines running would be possible.
They have safeguards built in for catastrophic situations. The compressors run on nat gas, which in turn pull gas from the wells and pressurize the system. Its almost like perpetual motion, except it burns energy to maintain itself. The pressures go into "safe mode" for lack of a better term. Six hundred pounds, or thereabouts, in the big interstate pipes.
It is arguable whether the suppliers would terminate service. The meters still run, you'll pay for it eventually. The companies don't just cease to exist. In a truly apocalyptic situation, they'd eventually valve-off to protect the wealth of the resource and keep it in the ground. In a skirmish, probably not. There are certain rules to interruption of service, and certain places which require service, like hospitals and military bases. They have their own bunker fuel to fall back on, but its probable that you'd see the gas remain online to facilitate a societal structure - although they could valve-off individual blocks that don't have important installations existing within its realm. If you were lucky enough to live near a place of such importance, you'd probably have gas.