If you are customizing it then that's pretty normal...
Remember, they have to get all those individual bits you've chosen that arent part of normal spec. If its something that isn't very popular, they probably keep very few of them ready, so have to order parts in.
EDIT: Ok,sorry - see what you mean now. If you pick ANY non-standard item on the 4 or 8 core model it changes to 8 days. Its usually 3 days for processors (I was looking last week).
EDIT 2: Could be a bug. Even picking a mini-display port adapter changes it to 8 days.