Hello girl in love
Yes, we do pick up things without realising it ~ via eye signals, gestures, body language, etc.
When two people 'hit it off', they talk about the 'chemistry'. Even love is about chemicals.
Whether he's really interested or an out-and-out flirt is another matter.
Look into his eyes ~ if his pupils dilate, he likes you!
Perhaps you could have lunch together!
Read up on body language ~ it's really interesting. Desmond Morris's 'Manwatching' is dated but interesting!