ATLANTA — Paul Griffin has come out of retirement to lead Georgia Tech’s athletic department through another transition. Griffin took over this week as interim athletic director at a school in a bit turmoil coming off a 3-9 season in football, a coaching change in men’s basketball and reports of internal strife under predecessor Mike Bobinski, who left Georgia Tech after less than 3 1-2 years to take the same job at Purdue. “I’ll tell you one thing,” Griffin quipped Tuesday, “no one is more surprised to be sitting in this room having this conversation than me.”