This guy at work has been joining me and some friends from my old job for lunch whenever I'm in the same office as he is about once a week. This is fine, I invited him the first time and now we both just assume he's coming along. We've had some rather interesting conversations that have been fun and some of those have crossed the line a little. Then last week I was in his office twice and he joined my best friend and I for lunch both days. I've told him numerous times that he can invite whomever he would like to lunch but he doesn't it's always just him. The first lunch he dressed casually, the second when it was the three of us he dressed nicer and I commented that I liked his shirt. Anyway, the second lunch he was super personable, outgoing and funny, otherwise he seems shy and quiet. Back at the office we were instant messaging and he used the word silly a few times. I found it amusing coming from him based on how he usually talks to me and so I commented that I thought it was cute he kept using that word. To which he responded by accusing me of having a crush on him.
Since I'm recently single and haven't really clued into guys flirting with me for years what's the deal, is he flirting with me? Interested in me? Did he say I had a crush on him to gauge my reaction to it? Or is it simply that he joins me and my friends for lunch and that's it.