Did he change his mind?

That last part might be over analyzing things too much. He probably wasn't near his phone just like how you weren't near your phone when he called you. I really doubt there's some complex reasoning going on behind the scenes; It's possible, but unlikely.

He's called you first for a reason, to talk to you. What ever his motive might be, he sounds interested, relax at let time happen.

We women are such relationship analysts! Sometimes it's a god thing, but not always. He probably just couldn't get to the phone and then got busy or something. Or maybe it's out of juice.

I really doubt it's you. In fact, he's probably called back by now, hasn't he? ;)