Why do guys flinch?

My crush and me were sitting next to each other. When touch his leg with my leg, he flinched (I flinched too). Then he moved away his leg a little bit. Then sometimes our legs touched again. And later, I realized that his leg his under my foot (is it crush thing? :/ ) by the way, he could move his seat to moce away but he didn't do that (if he wants to be far away from, he could do that, right?) Then I went to toilet and I saw that he changed our seats. He said that he is looking one of our friend's photo on phone. He also changed our plates... Then we never touched each other...
Why do guys flinch?
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