It looked strange to me from the beginning with Allen just dancing back there not really trying to advance the ball. But he stuck with it awhile which made it seem like he really was going to run it.
But yeah, I think it was a run pass option. Totally intentional, although it probably didn't turn out exactly how they drew it up.
Also, the oline didn't seem to be run blocking to me. None of them got up the field, which allowed Allen to make the pass without getting an illegal man down field penalty.