Guy's Behavior

Can someone answer this kind of behavior please? serious answers please?

I noticed one day this guy who I have a couple of times had deep convos started acting I don't know weird. first he does a double take when he walks past by, I once said hi to him he said hello... twice. yesterday I was in line paying my stuff at the register and he started at me as he was walking the opposite direction. I noticed him and waved hello. He smiled and as he was approaching me he was checking out my thighs. When he got closer to me I asked him if he could spare 5 min of his time. He took out his phone and said yes. We talked and he left back to work (this all happens at work btw). Later on I was leaving the break room and he was there talking to someone else. I was walking with my friend and he literally started at me. I felt like someone was looking and it was him. I really didn’t think much about it at the moment and smiled at him he continued to stare at me and then he looked down and started talking to a coworker. FYI on Christmas I gave him a Christmas card that said i admired his work ethics and the way he places people’s well being before his own (this is true I’ve seen it a lot), the next day he passed by and said ‘thank you for the Christmas card that was sweet of you!’ and he smiled. I don't know I just don’t wanna miss intrepid kindness from interest. Guys please help me i’m at a loss at the moment.
Can someone answer this kind of behavior please? serious answers please?
Post Opinion