I think you can rest easy - he's conceded already. you can't take back a concession speech. It's over praise God!
Ah, didn't Algore do just that in 2000?
Are you kidding? Sure, you can't take back a speech, but you can sure change your mind and give a brand new one - especially if you're John Kerry! Have you forgotten that Gore did just that very thing in 2000, first calling Bush to concede, and then calling back a few hours later to recind the call? lol...