Guy's Behavior

Why did he stare at me like this/get close to my face?

This kind of creeped me out a little and I wanted to have some other input to see if I am overreacting or anything.

For some background, a male co-worker of mine has acted really weird around me lately. We are friendly with each other, but we aren't super close and don't like hang out or talk outside of work or anything.

I noticed lately, he's been teasing me a lot more. Making "joke complaints" if he has to work with me (not really mad by it - he just makes a big deal about working with me playfully), looks at me a lot, made an off-comment about my smile (I gave him some work to do that is kind of annoying and he said you're lucky you smiled when you handed me that), he makes "jokes" about liking me or missing me/me missing him (he teases me and says "don't miss me too much" or says he'll try not to miss me or he'll tell me I'm lucky he likes me if I give him an assignment).

The creepy part was just this past week. He was walking to the break room and he stopped dead in his tracks when he seen me. He then got very close to my face, like how you do to kiss someone... just put his face really close to mine... like inches apart. Then he just hardcore stared into my eyes. No expression/smile, no blinking. Just stared intensely. I took a step back because that was really awkward and I didn't want him THAT in my face since we don't know each other like that. He didn't even say anything. He just stared me down. When I stepped back, I asked what he was doing and he just said "hi".

Why is he acting like this? And why in the world did he get so close to me like that and stare me down? It felt weird to have someone that close to my face when we don't know each other well. Any tips for how to deal with this?

Why did he stare at me like this/get close to my face?
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