Why do men smile when you put on something oversized?

So I’m 38F and my best friend is 36M. I’m supposedly friendzoned but we routinely make people question that with how we act around another and even I question it at times but that’s a lot to unpack right now. But, recently I was out at his house helping getting it cleaned up for a family gathering happening the next day. At the end of the day when he went to take me home it was cold so I went to put on my hoodie which is oversized for me but that’s how I like my hoodies it’s more comfy and honestly is probably about the size he would wear. When I can put the bathroom he looked me up and down and gave me the biggest smile while maintaining eye contact. Is there something I’m missing here?? Besides all the other stuff that happens that makes me question is just being best friends it’s at a point it feels like he’s just scared of trying with me in fear we’ll end up hating each other and never talking again or something.