Honestly? He probably has started to feel really weird and uncomfortable around you.
A few weeks ago, he heard from a co-worker that you were attracted to him. He didn't discuss it further with the co-worker (what with him being, y'know, a grown-up not a teenager) and politely changed the subject.
Since then, you seem to have been doing a weird combination of ignoring him, then staring at him across the cafeteria like a deranged owl, so much so that other co-workers have commented on it. You have ducked out of times when you would normally speak to him, but also set great store by 'locking eyes' with him.
Now you spot him across a carpark. He looks at you, probably hoping to catch your eye and have some sort of normal interaction with you, to dispel the weird atmosphere and stop all the staring that's been happening. But you're on the phone, so he goes inside. He sees you come in, but is mid conversation, so merely makes eye contact again to acknowledge you.
I don't want to be cruel, but you really have got yourself in a right tizz - over-analysing everything he does, setting great store by "looks" and eye-contact, wondering what it all means, and "why he would look at you unless he liked you" etc.
Step away from the crazy. Have no doubt, he knows you fancy him. Try to behave normally for more than ten seconds at a time, and see if you and he can have some sort of conversation. And if not, then it wasn't meant to be.