It depends on why they choose the term "shy."
If they're minimizing my problem because they think it's foolish or something, then yeah, that bothers me. But usually you just consider the source with things like that and you let it roll. People that say those kinds of things are usually dealing with issues themselves.
If it's because they don't understand or think they're doing me a favor by calling it shyness, then that's cool. Maybe they think shyness has a better prognosis and it's they're way of cheering me on, saying that it's something I can beat.
It all depends on who says it and why. Either way, what does the average person know about it? So good or bad, it really doesn't matter.