either way works. if the keg is indeed sealed, it'll retain carbonation after its brought back up to 68F.
you'd still want to rechill for 2-3 days before drinking it just to get all the traped CO2 in the headspace back into solutions.
Primary: English Mild
On tap: Pale Ale, Lancelot's Wheat, English Brown Ale, Steam Beer, HoovNuts IPA
Bottled: MOAM, Braggot, Raspberry Melomel, Merlot, Apfelwein, Pyment, Sweet mead, Cabernet
Gal in 2009: 27, Gal in 2010: 34, Gal in 2011: 13, Gal in 2012: 10