Whenever you have a problem with a show official, your best place to start is either with the steward or the show management. And you're probably best off talking to show management first, by going up to the people working the office and starting tactfully there.
It sounds like what happened was inappropriate. You can elect to stop with the people on site or you can file a complaint through USEF.
No matter how tactful or well meaning you are, going and speaking to the official directly is not a great idea, especially if you are unclear about the rules and the various roles of the people at the show. Your daughter's trainer is there to advise you on such matters as well, and probably you should ask the trainer before going to show management. If you don't trust the trainer's judgement on such matters, then you might want to rethink who your daughter rides with. That's not meant to be snarky, only thought-provoking.