I need to know ?? is he really interested?

You work with the guy its always bad news to date someone from work as they may bragg about it to other people in the work place and people would gossip and make umtions about you. Your reading to much into it, maybe he thought you were giving him the brush off so he didn't bother asking you for your number? Takes a lot for a man to ask a girl out so maybe you bruised his ego and he thought you were making up excuses?