Why does he ignore me?

So I met up with a guy for a casual thing. It was a little awkward the first meeting in terms for intimacy. I did nothing to offend him and he ignored me for a month. So I forgot about him thinking I upset him. Then the other day he asks me if I’m free. I was busy and didn’t reply until the next day. But the funny thing is he didn’t reply at all.
why would he ignore me if I did nothing to offend him. A simple hey no worries would be nice.
do I contact him? And if I don’t what should I do if he contacts me?

Why does he ignore me?
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