The Governor of the State of Oklahoma is hereby authorized reimbursement for all actual and necessary travel expenses incurred when on official business of the state.  Such actual and necessary expenses shall include the subsistence and transportation expenses of the Governor's spouse when accompanying the Governor on official business of the state, or when attending an official function at the request of the Governor.  The provisions of this section shall also apply to the Lieutenant Governor, the Lieutenant Governor's spouse, and the Governor’s personal assistant.