Good question and I'm not sure why I'm responding because I really don't know the answer. My initial feeling is that it doesn't, it's never happened to me and it's not mentioned on the forum as a common concern............but as we always say, everyone is different and hives may be one of the ways anxiety manifests in you. I'm sure someone else will respond with a far more learned answer. In the meantime, I think I would just assume it was something physical you came into contact with. Slap some calamine lotion on and see if it happens the next time anxiety strikes.
Hives are a pain, but they're harmless.
Peace
Greenlydia