While it's a little unclear, I believe that scene is meant to imply that Thor is essentially receiving a vision...
The dissolve to Banner, then the Helicarrier, showing the conclusion and aftermath of the battle are all bracketed by Thor reaching for his hammer, then pausing for some reason that is admittedly unclear, then finally picking up the hammer with resolve and calling the lightning to armour himself (until that point, his arms were bare, but the scaled armour begins to form itself as he calls the lightning).
So my interpretation of the scene is that he reaches for the hammer, pauses to process the vision he's received, then continues with renewed purpose. But I'll agree it could have been clearer.
But at that moment, he felt had to go to it, for he didn't feel worthynot answer your question? – May 16 '12 at 18:09