Yep...your mare needs a crash course in RESPECT!!! And soon, before someone gets seriously injured...kicking is NEVER the right answer, nor acceptable.
If she seems nervous around other people, then you need to have other people handle her, and help her "get over it"...she needs to learn that you aren't the only person who will ever handle her in her lifetime.
Find a trainer who will work with her, and help you learn how to handle situations that arise, like when your farrier came out.
Honestly, if my mare had done that, I would have put her butt to work...hard. If she wanted to dork around, then fine, I will work her butt...not just lunging either; lots of direction changes, backing, sidepassing, hip and shoulder yielding...
The reason for putting the horse's feet to work, is to loosen up his mind...if you KNEW your horse was getting nervous, you allowed her to go from a thinking frame of mind, to a reactive one. If you notice her getting nervous around another person, just get her feet to move...just make sure you are controlling the direction; and don't just lunge, do lots of direction changes, and other constructive movements (yields, backing, flexing, etc).
Example...the other day, my mare decides my hubby is a scarey horse eater, and FREAKS out...snorting, backing, twitchy...well rather than force her to walk up to him, and potentially hurt all three of us. I just got her moving; at first I did some lunging with lots of direction changes (at the same time I had hubby stand in one place and do what he was doing when he "scared" the horse...he was waving at us!). When she started relaxing a bit, I then switched to sending her back and forth between hubby and I. When she calmed down further, I stopped her, and had him just walk back and forth waving and talking loud. When she licked her lips and cocked a hind leg, I had him stop, pet her, and then we started all over again (from the stand still). It took all of 5 minutes to take my mare from reacting, back to thinking about the situation.
If you can unlock your mares feet you can unlock her brain.
"The ideal horseman has the courage of a lion, the patience of a saint, and the hands of a woman..."