Is my Coworker Attracted to me...????

I just got a new job. There is a cute guy who works there but he looks 10 yrs older than me. We share the same hallway but he works in another office down the hall from me. He seems quiet & very reserved and he never talks to any of the other women. One day he went to the kitchen. I also went to make coffee. When he saw me his eyes widened, he kinda checked me out then he asked how my first week was going. Then he ran his fingers through his own hair & asked if I had a "wild & crazy" weekend. That was 2 weeks ago, since then he hasn't said hi or made eye contact when he sees me. He would also act very nervous & awkward when he was near me. I thought he hated me. My coworker said hes married so I thought he could never like me. Today I kinda bumped into him in the hallway as I was coming out of the washroom. He made some comment how it must suck that the women's washroom is too far. I replied by agreeing with him. I kept walking then he said , "Oh have you seen our office?, you should come see it" He meant the office he shares with 10 other people. I said no, he opened the door and said "come in" & he was smiling very wide, he seemed really happy to be near me. He kinda checked me out too, as I was looking at the office. I kinda looked in and we chatted for a very small moment then I left. Did he use the "seeing his small office" as an excuse to talk to me more? Why did he go from not talking to me, to inviting me to his office & being very happy to see me?
Is it possible he's attracted to me or is he just being nice?