No official action performed by any judge of the twenty-fifth judicial district of the district court division of the General Court of Justice shall be declared to be invalid by reason of the fact that the judge was beyond the mandatory retirement age set out in N.C. Gen. Stat. § 7A-4.20 at the time of his performing any such act; provided this section shall only apply to those official actions performed prior to May 1, 1977. (1977, c. 389.)