I am not wrong.. I observe my T's plenty enough to know that breath on a tarantula that is not in a tube web will affect them.. They will react.. One that is in a tube web will not react..What I am saying is your are wrong and should observe your T's a little closer. You are humanizing...perhaps projecting stress.
They may be reacting the way they react because they might feel what they believe to be the presence of another preditor.. So yes.. That would lead to stress...Reaction doesn't equal stress.
Of course disturbing a tarantula in the process of molting is not wise. That is common knowledge, that even the OP was aware of.