I have cold, dry winters and warm humid growing seasons. So even if I have a firearm that I have not shot recently, I clean it completely each spring, and then again in the fall once the heating season starts. I keep my pieces each individually locked. Longarms muzzle down on carpet so steel has no contact with an outside wall. I do not store in cases as I had trouble with that in the past. If the rust is not bad, sometimes simple rub down with oil will fix it. I would keep my eye on that spot though. I use very light oil as a lube.