I wouldn't be too concerned, its possible that an item you have in your build is out of stock at the moment - a way to check would be to duplicate your build in the configurator and try and apply a fast track to it.
If it doesn't let you it should tell you which items are 'out of stock' etc.
Getting in touch with PCS would be my next suggestion they are usually on the ball with this sort of thing and can give you a estimated time of arrival if anything is out of stock or if there are other issues affecting your build.