You sure about that? Even via e-mail? Or a phone call that you may have been a little rude to the person because you had never met them?
Because I.T guys are well known for their temperament and patience when it comes to speaking with plebs on the phone/e-mail.
For the record I am in IT. So I get how it happened. You just got to be more careful about that. Even if you think you were joking or being funny. the wrong person reading it could take it another way and get you outta there very quickly.
But on the off chance you actually didn't do or say anything wrong to this person, well then fuck them. I hope you gave them a nice virus or at least reset all their passwords/encyrpted all their e-mails before you left.