Natural gas travels from supply pipes in your home into your appliances via flexible, corrugated metal connector tubes. Because they're usually out of sight, you might not think about them.
It's important to have your connectors checked to make sure that older, uncoated brass versions are replaced with new stainless steel or plastic-coated brass connectors. You likely won't be able to see your connectors, so call a qualified professional to remove the old connector and install a new one, if needed.
For your safety, please don't move your appliances. Movement can cause an old connector to break, creating a hazardous situation.