RE: Do I need to re sight?
Your going to have to at least check it, maybe you will have to adjust it maybe you won't. Why wouldn't you anyway? You should at the very least shoot your gun before the season to make sure nothing moved and to get a little practice anyway. If not all year long on a occasion just for the practice and fun of it.
Anyone that pulls their gun off from the rack or out of the case opening day for the first time since last season is just asking for trouble in my opinion. These are normally the same people that wonder why they miss or wound deer.
Paul