Is he interested?

,We work in completely unrelated departments.(we have very minimal work-related contact) However, we seem to run into each other walking in and out of conference rooms, hallways ,elavotors and staff rooms. He now always make it a point to smile ,ask how I'm doing and If he is not rushing off somewhere for work, we'll end up chatting briefly about basic stuff.ie if we have gone to gym lately etc.I see him see him around 1-3 times a week if I'm lucky.

Today I ran into him on my way back to my floor after my lunch.I said hey and asked him if he's on his to his lunch to which he replied yes.Then proceeded to tell me that he is going to grab a sandwhich at the food court across the street.I then said "enjoy"Then he asked me if I'm taking my lunch and I said 'unfortunately I just finished and I have to go back on my floor.He looked disappointed and said "OH NO!i think he wanted to ask me to go with him.

is he interested ? I 'm thinking to give him my number