I was given a Winchester 94 in the early 50's for Christmas. I used it all my life, and it still has no rust. I use Ballistol to protect it from rust. It was invented by Germany in WW1 to protect their guns.
Maybe..... When you have taken the action out of the stock (assuming you have), did you look carefully at the inleting? I assume the stock is solid walnut, so if there was any bare wood inside the stock, it can and will absorb water if it gets wet or the air is too humid. I have made several hundred stocks and I ALWAYS put finish on the inside of the stock to seal it. If the stock is a laminate, you won't have any problem, same for composite stocks.
No I haven't checked that. Just got the rifle tonight. Ill check and seal it if needed. Thanks for the heads up.