I looked at a 40 year old house today. The block basement has numerous cracks in the joints. They aren't big, but are certainly there.
The owner says the previous owner told him 2 years ago that they were there when he bought it 6 years before that. So if no one is lying, they are at least 8 years old. There is no hint of problems upstairs, but the house was heavily remodeled by the current owner, so it is impossible to say much. No sign that anyone tried to patch them.
How concerned should I be about this? Any way to find out what they mean? The house is build on shale; it ought to be stable.