Why Obama is saying sorry to Nancy Reagan?

It's all over the papers, internet, radio and television. I can't believe the media was actually talking about it. Don't they usually do their thingy covering up for him so he will always look good? I guess not since election is over and perhaps media budget ran out? I dunno. I'm just saying. So, what was it about? Why is he saying sorry to our beloved former first lady? Let's find out the detail from Michelle Malkin's blog here.