You may be excactly right, Revel.
For the last few months, Iranian news services have been trumpeting how getting a delay until March would be a good thing. Makes one wonder.
March is the due date for Iran's nuclear test - probably of the underground type. ETA March 19th. While the nuke expected to be exploded is a "big old thing", it will be meant to underline Iran's scare tactic, threat profile rather than their actual capability to deploy a missile launched nuclear weapon.