I might be way off (I'm a fairly new dog owner...) but I'm not really surprised she got annoyed at a puppy clambering all over her while she was on the lead. I don't know anything (at all!) about ringcraft or ringcraft etiquette but it seems rather bad manners to allow a puppy to climb all over other people's dogs while they're all on lead. Is there any part of the class that actually requires the dogs to meet on lead?
At our training class, the rule is absolutely no nose-to-nose meetings while on lead and it's something we work on outside the class, too. We work on exercises outside with walking to heel on and off-lead while maintaining our dog's full attention. In "meet and greet" scenarios, we aim to have the dogs sitting and waiting rather than bolting to meet the other. In the real world it's obviously much harder but having your dog focus on you makes the training way easier.
Sorry, this isn't particularly helpful but I wanted to say I doubt very much you have failed her!