It seems he has some interest in you, although I will say that to a lot of people, flirting is just flirting and they enjoy it even if they don't want it to go anywhere. But, it's very possible he doesn't know what to think about where you stand with your ex. The way you put it, "that's another story," was a really vague answer and if you had said that to me I might think "well I guess that situation is complicated and she doesn't want to talk about it".
If you're really interested in him and want to date him, you should probably come up with some way to make it clear that you're definitely broken up.
Welcome to the board!Its hard to say whether or not he is interested at this point, given the information you presented. Sometimes people at the workplace flirt with each other but it rarely extends beyond that. I agree however, that your vague answer may have thrown him off a bit and he isn't sure if you are involved with him/someone or not.
Do you want a relationship with this person? Or just to date? I think before anything else, maybe its a good idea to just take sometime and focus on you, seeing as how you were in a relationship for so long and are now single. But, if you really want to pursue this, I believe you should let it be known that you are in fact single and see where it goes from there. Good Luck!