Go and look at it. I've got cars that look all rusty when photographed in a shed under artificial light with a crappy camera but there's nothing wrong with them. All it takes is a couple of weeks outside with some cracked paint to make it look bad but if it's been in the shed and dry since then the rust may not have progressed.

Of course, it could be completely F*$%#d as well but better off going and knowing that it was stuffed than not going and wondering if it had been all right.