Same thing happened at a "smallish" gun show here in Phoenix, at the VFW hall a few years back. I remember hitting the floor.
The "theat", then as now, is really not professional dealers, but the private sales guys, for whom some of their inventory could very well be there personal "carry" battery.
Be especially weary of them and anyone hanging out at there tables, as they also draw the neophytes whom, for whatever reason, are desperate to avoid the paperwork. They seem to avoid the safe gun-handling classes as well.