Going back to the first post on this thread to me it reads like he was guarding his bone not lashing out through pain or fear but without being there who's to know, he might not do it again if he got scolded at the time.
A mate of mine has a springer which is a lovely family dog and adores his daughter but he challenged her a couple of times over things he didn't want to give up or get off the couch etc and after a good bollocking off her under his supervision the dog learned his place again.
My last lurcher "was" an unpredictable flighty bitey b*****d.