Here is the IRS page
that covers this credit. The only date limit I could find was that the vehicle had to be put into service after 2009, but no end date, except when there are 200,000 vehicles sold by that manufacturer (which is less than the total count of all EVs sold in the US, ever). One possibility is that Fisker dropped the ball (shockingly) by failing to file the quarterly reports required. Otherwise, there does not seem to be a valid reason to deny the rebate.
[Edited to Add:] There was a separate rebate for charging equipment
that expired on Jan. 1, 2012, but that was under a different program and was ultimately renewed, but with a lower overall cap.