Excellent post @Quincy .
If I may, I'd like to add...I noticed rust on my meter and the attached pipe last spring. I was prepared to stop by the hardware store to pick up a can of matching spray paint (a boring gray). Fortunately, something made me call the gas company to ask for permission first.
They said "No! #1 Rust can be a sign of a gas leak. (They sent out a technician within the hour.)
#2 Painting over any equipment owned by a utility company (gas, electricity, water) could invalidate your insurance coverage."
The technician arrived promptly, found no evidence of a leak, removed the rust and spray painted the equipment (free of charge). It looks as good as new!