I don't get it...

I don't get it.... I really don't.
So today at work Co-worker said "don't send messages like that" and there was no smile on his face. I immediately smiled and said sorry, but I thought he was talking about the first one the one about having water in my ear, kinda poking fun at him. But he wasn't. He was talking about saying that I miss him...
I mean wtf?
He said that it was a bit heavy to say, making gestures towards his stomach, as if I had hit him or something. And I just answered that it wasn't meant like that, that it was just a general feeling, after 7 days of constant contact. He just said, "I know, but you don't say that you miss me, you say that you're thinking of me or something".
I mean really what is up with that??
I'm just assuming that it's a cultural thing. Maybe saying "I miss you" is more of an indication of being in love than saying "thinking of you".... I'd have said the opposite... But then again I'm not italian.
In any case no harm done, but I do feel like I got punched in the stomach today with that comment. It's frustrating, because I was feeling relieved to have gotten it off my shoulders, and then I get knocked for it.
Hopefully my trip will give me perspective on everything. We're leaving next thursday and time is just moving waaayyyy too fast for me. I can't keep up with work, people, blogs, and packing which I haven't started but have been thinking about for weeks....