Is it normal for a guy to call you twice....but hasn't called again?

So, there's this guy. We have been friends for a while, but there has always been something there. Anyway, we have been flirting all semester, and I have just been waiting for something to happen. He shows a lot of interest, always tries to sit next to me, compliments me, teases me, tries to be close to me, I even caught him staring at me from across the room before. So about three weeks ago when we were talking he said that he had called me twice and was very sad that I hadn't answered. Turns out he had my old number programmed in his phone ...and corrected it immediately once I told him that was the wrong number. So, the next day I called him back. I simply told him that I was returning his missed calls, he chuckled and I seemed really surprised that I had taken the time to call him back. I asked him why he called me to which he replied, "Um, uh, well I just - wanted to talk to you - there wasn't really a reason." It was an awkward call and I let him go after that. We saw each other again about a week later and it was back to our routine flirting. But that was three weeks ago and he hasn't called me again since. So...I'm really confused. Tell me, is it normal for a guy to act this way?