The national GOP is still a bunch of amateurs. If they were on the ball, they would have found out about these issues and disclosed them during the primary. It really does amaze me how bad the national GOP is when it comes to spotting issues and getting on top of them for elections.
Wait, I thought folks didn't want the national GOP (aka: the GOPe) from getting involved in the primaries. Sanford was not the establishment candidate this go around. Mark "Appalachian Trail" Sanford is a selfish tool that fooled conservatives values voters in a southern, overwhelmingly Republican district to give him a second chance. LOTS of conservatives fell for this guy again - including people like Erick Erickson over at Red State who endorsed him.
For the national party it's damned if they do, damned if they don't. If they get involved, even to stop a ridiculous candidate like Christine O Donnell, the grass roots gets pissed. If they don't get involved and a bone head like Mark Sanford wins the nomination, people complain the national party didn't do anything and wonder why the RNC isn't as effective as the Democrats in terms of avoiding throwing away seats.