So there's this guy (who I don't know very well and have never talked to). He used to do little things to get my attention (or so it seemed) and I always tried to pretend like I didn't notice. When I "wasn't" looking at him, I could see him out of the corner of my eye checking me out (like a head to toe evaluation or something). Sometimes he'd walk right next to me. One time I was looking down (staring at my shoes or something), and when I had put my head back up to the right, I saw that he had like, stopped completely to look at me, and then walked away slowly when I saw him. But once I started to pay more attention to him/look at him, he's kind of stopped doing it. Like the little things he used to do he doesn't do anymore. I don't get it! Did I scare him off? If I go back to "ignoring" him will he chase after me?

First of all, guys are weird. They're unpredictable and confusing. But as they say "You can't live with them, but you can't live without them."
My advice to you would be to casually talk to him, say hi or something, just to get his attention. Don't scare him off, but let him know that you notice him.

Try this, and get back to me on how you did.

Hammy

If he's that shy... then chances are, he won't chase you. He'll be just one of those shy guys.

Are you interested in him? If so, then ask him out. If not, then let it be.

Good evening free_money...
You didn't scare him off, he probably started to notice you paying attention he didn't know what to do. As most shy guys tend to do, he retreated simply because that's where his comfort zone is.

It's my experience while working with a lot of different people, some very shy, that to help them be a little more open, you need to encourage them. When you see him again, don't wait for him to say anything, approach him. Start slowly and just ask him a simple question and go from there. The more comfortable you make him the more comfortable he will feel.

However, I hope your true intentions are to get to know him, like you said. Shy men and women tend to have more fragile ego's. Setting this guy up just because you find it humorous, or just like his attention, but are not really interested in him, please let him be.

If you really do want to get to know him and think you might be interested then the key is to make him more comfortable. By doing that I'll bet you will be surprised at the outcome. A lot of guys seem shy when you first meet them but after spending some time with them and they become comfortable with you, they don't seem shy any longer.

When I first met an old friend of mine I felt he was very shy. I being the extrovert and flirtatious personality I approached him. It wasn't long after that he began to open up and now there are times I wish I could get him to shut up (all in good fun) So first, second and even third perceptions can be deceiving.

Good luck and don't take his retreating as something you've done wrong. In fact it sounds like you have something he is quite interested in, just move slow.