From TwitterMannersIn English-speaking culture it's customary to ask about someone when s/he asks about you. Not doing can be considered rude:Good: Jon: Hi, Don! How are you? D: I'm good, thanks for asking. And you? J: Great! Thanks! Bad: J: How are you, Don? D: Good!
The feeling could be:
'Gee, that guy is self-centered', or 'Doesn't he care about how I am doing?'