Hello John, As long as the age signs are right the vase is fine. I have heard that this type of decoration is also faked now. You are correct in that it is a Chenghua mark, but it is a faux mark. The item cannot be from the Ming dynasty.
This pattern started to be widely used in the first half of the 19th century, about Jiaqing/Daoguang reigns and was used until republican times. I would say yours is either 19th century or late Qing (Guangxu reign), judging from these pictures.
