Nice to meet you?

Almost 3 months ago I started my new job. I showed up at work, got a tour of the office, sat down at my new desk, got my computer all set up and started meeting and getting to know the people on my team and the people that I sit near. Well, almost all of the people. Somehow I was never introduced or didn't introduce myself to the guy who sits in one of the cubicles next to me. We all sit in little sections of 4 cubes. In my section is one other girl from my team, the handy dandy IT guy for our floor (who introduced himself to me two different times) and the guy that I have never officially met. I know his name because we all have name tags on our cubes (and I'm assuming he's figured out my name by the same means). I have a vague idea of what he might actually do in our office (although my office manager told me he's about as useful as tits on a nun). I know that when there was a really big cockroach in our office a few weeks ago he came to the rescue, thereby making him slightly more useful than my office manager thinks. I know that he was or is a sailor of the military variety because I can overhear his stories of being on the ship. I know he recognizes me when we pass in the hallways. However, we never speak to each other. There's really no work-related reason we would need to speak but we don't even say good morning to each other.
Does this all stem from not having ever been introduced to each other? Should I have just stuck out my hand on my first day and introduced myself and said nice to meet you? Should I just randomly ask him sometime how his weekend was? Or, do I just go on pretending I don't even notice? Does he also sense the strangeness of the situation or is this normal? It's a very large organization so I don't expect to know everyone but I'm used to at least having a cordial conversation every now and then with the people I sit 5 feet away from 5 days a week.