No but many mechanical codes require 3ft clearance from a gas manifold vent to any 'source of ignition', and an AHJ will consider a subpanel to be such a source.
Usually they're right next to each other.The meter may not include a vent. The pressure regulator definitely does.
I just looked up NVE's gas meter clearances. It states 3' from building openings, electrical panels, ect.We have a NVE requirement for metered panel's that is 3 ft and conduit must be 12' inches away from the gas meter.. But There is noting in the requirements of a sub panel. The only code i would see is woking clearances. Inspector failed us because of 3ft rule I think he is pulling that out of the air..
A while back, our gas supplier went to the 36" distance. They installed PVC pipe extensions to their existing vents.Usually they're right next to each other.