How to handle coworker crush?

he is 43 and i am in my mid/late 20s and we are not in the same dept. i thought he was cute but alot older and thought he hated me in the beginning, though sometimes i would catch him checking me out. made an effort to be friendlier but any time i was sweet and fun, like i would be towards any person i thought was cool, he seemed either nervous or weird about it or would blush/touch his hair. i was never overtly flirty because it's work. i started ignoring him except for work stuff. then, i caught him looking at me from a distance several times outside then turning away when i saw and he always checks me out. in the hall, he would smile shyly, look down and nod. so, i had a talk with him and said i was being friendly and thought it was misinterpretted (mostly because i was scared of rejection and he might have a gf, etc.) and that i was scared of him now. he laughed and was like just be cool, i have absolutely no problem with you in any way. dont know how to treat him now or how to be?