Yes, I too am wondering why the horse was not lame during the lease?
Honestly, I don't mean this as rude, but this is directed at anyone looking to purchase a horse. It does not matter WHO you buy the horse from or how close you are with that person, or if they are a highly reputable breeder/trainer. Doesn't matter. There can be things that even they are not aware of, whether they disclose these things or not, there can always be something that even the poor owner has no idea about. Always, always, get a PPE.