Lifestyles of the poor and nameless

I was watching a movie on my computer, when suddenly I got the following IM from a "net buddy": "Just got back from the movies". Call me old-fashioned but I thought it was pretty rude of him to just jump right into conversation like that. We aren't friends in real life, and I wouldn't call him a friend online either....just someone I chat with from time to time.

I suppose the proper thing for me to say was "can't talk now, I'm busy". But since he didn't feel pleasantries were necessary, neither did I. I responded with "congrats". He took offense to that because he thought I was being rude. I'll admit that my sarcasm can be misplaced at times, but it really seemed like a logical response. "Just got back from the movies" didn't seem to invite dialogue...it seemed like an announcement of a minor accomplishment. So the natural response: "congrats". It's not like we were talking before and he was giving me an update. It came out of nowhere. He said I was being ridiculous to expect him to formally address me with "hello" or something like that everytime. Call me crazy then, because that's how I do things. If we're friends and I know a person won't mind the intrusion, or I need to communicate something quickly, then I'll skip the intro. If I don't really know you, I won't make any assumptions.

I think we need a book on IM protocol. And please tell people that it's not OK to address a person as "what up ma" when they send you an IM for the first time.