I think you jumped the gun. It's obvious that he did like you, at least enough to seek you out to talk to. That doesn't mean he was working up toward asking you on a date, but good chance that he was.

It's part of Nature's design that males get excited by being in chase mode. The way things were, he was the pursuer and you were the pursued. He was enjoying it. I think you got impatient to find out what this might have been leading up to, so you stopped letting him be the pursuer. You turned and went to meet him half-way. ("Yeah, I like you too.") That seems innocent enough, but it may have taken some of the fun out of it for him.

It's like you said, "So . . . are you gonna ask me out, or what?" I can see where that was a mood breaker for him. He's turned off now.

Some men would have been real happy to get the reassurance of interest that you offered. He wasn't. He wanted you to continue being just a little bit of a challenge. You took the lightness out of it.

Above all, don't go asking him, "What did I do wrong that you don't come around me like you did?" Ease back and see what happens. See if you can resume some light-hearted flirting. Keep it light.