I've come across to this article just recently. As a psychology student and through my interest in personalities, I find this article very interesting read and likewise funny too.
I classify myself as an introvert too. Funnily enough, I work in customer service enviroment dealing with our customers and colleagues all the time. Sometimes it can be very draining and tiring. Please don't get me wrong I actually like people but on the other side I like to spend some time on my own and in solitude.
Reading this article I recognised some signs of being misunderstood. I constantly get asked if I am ok and what´s the matter. I can´t help myself but only smile on my answers that everything is alright and that I am not lonely.