Actor Dabbs Greer plays reporter Mr. Waring, who is interviewing Rob and Laura Petrie about, amongst other things, how they got married in an Army camp hospital. And in that episode (Season 2, Ep. 3; The Attempted Marriage) they were married by Chaplain Berger, played by Dabbs Greer.
Laura wears her new bubble hairstyle in the framing portion of the episode; however, she doesn't change her hairstyle to a bouffant flip for the flashback portion, which is how she wore her hair in previous flashbacks.