Guy's Behavior

What does it mean if a guy purses his lips in and gives you a head nod when you smile at him while he bops his hands?

my crush saw me from a distance and walked directly infront of me the way I was going toward him. as soon as I looked at him I smiled and he acted like he hadn't been staring at me and when I smiled at him he looked at me pursed his lips in and gave me a head nod while he was playing with his hands (hitting his hand to the other). does this mean anything or what does this mean exactly?
What does it mean if a guy purses his lips in and gives you a head nod when you smile at him while he bops his hands?
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