"Good morning, Grandfather."
No it won't, because you're addressing the grandfather here directly and you always show respect to older people in Japanese by using the polite version. So it's お祖父さん（おじいさん）and not the humble form 祖父（そふ）. The latter you'd use when talking about your grandfather with someone else.
Sofu, the humble form, is used, when you talk about your own grandfather with someone else to show respect to the listener by not putting your family members over theirs.
Ojiisan, the polite form, is used, when you adress your own grandfather directly to show respect to older people or when you want to refer to someone else's, to show respect to their family members.