maybe the previous owner had a big ass!
overall this is expected of leather----as it is natural and creases/wrinkles are bound to happen. you may be able to reduce the creasing by using some good conditioner like made by 'Leathermaster'. if you are really worried about it there are repair kits available that can 'fill in' creases and then you have to paint on top of it to cover the filler. I have never tried these but I know people who have and they seem to work.
I tend to appreciate natural creases in leather if they happen....as it adds some natural patina to leather.