Err... Mirror lock-up is use to prevent this kind of blur... not create it. You should use mirror lock-up or live view when shooting at slow shutter speed.did you confirm that Mirror Lock was on? didnt see that in any of your replies. anyone else having issues like this in the future should understand that this is a likely cuplrit for camera shake at slow shutterspeeds on a tripod.
you also have to be careful of your own movement when making exposures like this. even if you are not physically touching the camera or tripod, walking around the camera position can cause vibration in the ground (depending on the surface you are on) and that can be transferred through the tripod and show up in exposures. this is not as likely outdoors but i have seen it happen on several occasions indoors when i or someone else walked by my rig during a long exposure.
Didn't use mirror lock. It might be helpful in some situations, but it wouldn't have caused this kind of motion blur.
Have a nice day.