What do I do, I feel like a jerk?

Okay so me and my boyfriend broke up last week, and ever since I've been on the rebound kinda, but this guy from my work that I had this huge crush on hung out with me last night. We talked until like 4 in the morning, and when he was about to leave, he asked me for a kiss and whatnot, and I laughed and was like "Don't be so nervous geez!" and then we kissed, but the problem is, there was no fireworks, you know? I don't know what to do, that's kind of very important eep.