Was he showing interest?? or was he just being a guy?

So I worked with my co worker today for a brief moment. I bent to grab something and he was just standing in front of me looking down my shirt...after I got up he started sucking his lips so bad like constantly and making it obvious and making eye contact...but I just went out with our convo. was the whole "biting and licking lips" movement a subconscious guy thing to do or was he doing it on purpose to show interest?