Not dumb at all, I think it is a good question even just regarding general social etiquette. Sometimes. I never had an urge that I necessarily had to explain but generally feel that saying something is polite. I usually either provided no explanation when I was in a relapse and did not go to session because I decided to drink or was too hungover. Pretty much the same in everyday life, I cut it too short or lie when I have something shameful to hide. I only had a T pushing it a bit once and he was right as it was one of those times when I lied. I shut it down though so he could not do anything else.