Hard to say without being there, because was DD really overwhelmed, or would he have adjusted to the commotion? My puppy manners class was held in a public park. There was so much going on, so many people and so much noise - but my pup was 16 weeks then, a little older than yours. I'd had him since he was 8 weeks and he was accustomed to being taken around, so it didn't phase him. You'd be the best judge of whether or not DD should have stayed - if you opted out of the class, then I trust your judgement.