So, for our wedding someone gave my wife and a cast iron lodge pan. Its a very nice pan and cooks well, but it's started to develop a rust spot after only a few months use. This is gross. I scrub the spot off before use, which is a pain, but Better than eating rust flakes with our hamburger helper. My inner mechanic is screaming "if its rusting, oil it!". Obviously I'd prefer a veggy based oil to my traditional motor oil, but is oiling a cast iron pan before storage sop?
As rumtsho has said oiling will help, but I think you have a more fundamental problem with is learning the care for your cast iron.
There are lots of resources on the web to learn how to prepare, and maintain your cast iron. Some of it works even though it's wrong, some of it is very good and some of it is scientific in nature. However here are the basics.
You want to scrub your pan down once. Oil it all over...every nook and cranny even in the handles .... with a very thin layer of oil. Then wipe this off with a clean towel and bake the sucker at 385 for an hour or more until it looks bone dry.
I recommend you do some good reading however and learn all the different ways to keep it in shape along with all the different fat and oil choices.
I use peanut oil, it has a high smoke point, which means the polymer you create will burn at a higher temperature than those oils with a lower smoke point, and peanut oil makes a hard seasoning.
You can oil it or not, it is up to you. Oiling it will protect it from rust if there are faults in the seasoning, and will make a nicer seasoning because the very thin oil layer will contribute to the seasoning at preheating better than the cooking oil does during cooking. On the down side, it will go rancid during storage (you may or may not notice it, depending on how long it goes between usage and how sensitive you are to the tiny amount of rancid oil) and it will fatten the other pans it touches.
To also address your body, when your pan has visible rusted spots, you should strip and reseason. The oiling is done on intact seasoning.