I've had my fair share of run-ins with awkward IT folk that miss a lot of social cues. It's easy to become overbearing when you're not used to picking up the signs. Here's an article over at HuffingtonPost.com on 5 Times You Should Just Keep Your Mouth Shut, including a great "3-for-3 test":
The next time you're at a cocktail party, wedding or office get-together and you arrive at that moment when you've met someone new and realize that she has not said three full sentences in the last three minutes, stop. Take a breath.