I'm talking about whilst he's running. Not once he's stopped running. To me, it seems that he's running for no reason. Then he stops, looks over his shoulder and the girl is there. If there were a few shot of him looking over his shoulder while he is running, it would portray that he is actually running from something, rather than just going for a jog. It may also imlply that he's gotten away, since there's nothing actually there. That would ramp up the tension.
Don't get me wrong though; it's fine the way it is. My suggestions would just to be to try and slow the pace a little and give us more of a chance to understand what's going on. But, if you're happy with it, what you've got above is the feel you were after, then stick to your guns.