A piece of cromoly sitting in your house will rust on its own with no help over even as short as one year. It wont rust like mild steel (standard steel) but ten years of salt water would make a hell of a mess out of the stuff.
i have a full 4130 chromo frame and its had a few spots of rust on it since i got it, and they look no different now and i got the frame 5ish years ago...
Like previously stated in the thread, true 4130 CrMo tends to only corrode on the surface. Something steel wool will take care of. I own a freestyle BMX from the mid 90s and it still holds it's shining chromed looks, even though the bike has been outside for years without much care.