Guy's Behavior

Why didn't he kiss me back?

Last night, I was cuddling with my crush and finally built up the courage to kiss him. He had been sending me signals all night (cuddling, holding hands, long gazes, leaning his face against mine), but when I leaned forward and kissed him, he did not kiss me back and started to act a little strange. I asked him if he minded that I did that, and he said no. I am relatively sure that this was his first kiss, and I did kiss him a little bit by surprise, so do you think he was more shocked and did not have time to react or is not interested in me? After this, we continued to maintain the same flirty contact, and there were several instances where our lips would be within millimeters from each other, and I'd wait for him to finish the kiss, but he never did, and there was NO WAY I was going to make the move and risk the same awkward situation happening again. What do you think my crush was thinking?
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Now, he's asked to hang out with me again tomorrow, which surprised me. Maybe he was just nervous and freaked out when I kissed him before. Would you guys continue to lead a girl on like that if you weren't interested?
Why didn't he kiss me back?
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