Was it just dinner..or a date??

This has been on my mind for a couple of months now, so I thought I'd see what other people think....

About 2 months ago, a guy who I kind of know (but not that well) called me up, and said he would be working in the area that I live and did I fancy meeting him as he would have a couple of hours spare with nothing to do.
I suggested that we have lunch as it would be lunch-time and he would have have nothing to eat (I didn't think much of having lunch at the time as I have quite a few male friends I have just lunch with).
Anyway I met him and we sat talking, he started telling me about his family and where he grew up and went to school, then asked me about my background and homelife etc,etc....
After a while, I started to think "is this a date?" After the meal he wouldn't let me pay, and as we were leaving he said he'd enjoyed it and "we should do it again sometime".
I left, feeling a little confused as to what had just happened, I know he's seeing someone who he speaks about a lot....and I'm not interested in him while he's got a girlfriend.
He calls me quite often and sent me a text message while he was out of the country on a trip.
He called me a couple of weeks ago and told me that his ex had made a pass at him, and how I had permission to slap him if he cheats on his girlfriend. I added to the conversation that he and his girlfiend seemed really happy...and he said they were.
But then I recalled that a couple of months before our "lunch", I remembered him looking at me very obviously, and trying to get my attention.
Do you think he wants to be more than a friend, if so why does he tell me about his girlfriend?
And was that a date??
Any info would be usefull on this!

Just for the record, I will NOT start any kind of affair with him while he's not single, and I'm being careful not to text or call him back. He seems like a relly nice guy who I could be friends with but I'm worried he wants more....am I reading too much into this?

sounds like he's just being friendly. don't read so much into it. i don't think he's interested, if he openly talks about how happy he is with his girlfriend. or he's an idiot.

Hes just being friendly. Besides he has a girlfriend and ask yourself do you really want to start an affair like said. So just treat it as a friendly gesture.

Hum....I remember this character. It reminds me of something I would of done if I wanted some friend as a my rebound. But let me ask you. When he asked you about giving him a "smack" if he ever cheated on his girlfriend, he did act kind of cocky or sassy while he was talking? Also, at the time of your encounters, was he always serious or still acting cocky and bubbly. Did he ever said, "thanks for being my friend" or "thanks for being there to listen"?