Sadly in life there will be many of set backs. Stuttering, anxiety, drug habits etc.. we're always going to have set backs or relapses. In those times our mind was/is hardwired to stutter (in your case) so eventually it'll come back up. Use this time as an opportunity to tell your mind (im having a minor setback i use to stutter but it went away, now its back temporarily.) Stuttering is so strange though to be honest. Theres research on many things but stuttering is one of those things that really puzzle me. Sorry if i wasnt much help! Look on the bright side, atleast you didnt stutter like some of us all our adult life. Be thankful it decided to come back now at 72.