Am I the only one who had a neighbor try to reset a loose shoe on my day off?
Came back to find they'd used the wrong nails and now the horse is favoring that leg. In my experience, well-meaning folks can cause real harm without proper know-how. Your mileage may vary, but I'm putting out a warning to lock up your tools and set clear boundaries. Take this with a grain of salt, but a simple conversation might prevent a bigger problem down the road.
Sometimes a horse will act off for a day or two after any farrier work. They're tough animals and a few odd steps might not mean real damage was done. It's good to be careful, but maybe this will sort itself out.
Umabailey's note on horses acting odd after farrier work reminds me of a time my neighbor fixed my garden gate. He used the wrong hinges and it fell apart in a week. It's true that good intentions don't always mean good results.