My grandparents paid off their mortgage and signed their house over to me. Their will written prior to this states the house and all it's contents go to my aunt. Is this going to be a problem for me after they die? Do we necessarily need my grandparents to update this in their will?
It's going to be a problem for your aunt, not for you, since your grandparents don't own the house anymore. The wills should be updated though, definitely.