I hope the simplest answer is the reason: They are just WAITING for 03/19/2015 (third year after POR effective date) to pass by because on 03/20/2015 or later they can trigger a new "Testing Event" (ownership change) without jeopardizing the (at least) $5.9 bln. NOLs.
Friday after-hours or Monday pre-market could become very interesting IMO