I just updated to the latest version of NGUI (3.0.7 f3). I deleted the entire NGUI folder from my project then downloaded / imported it again from the asset store. I created a new 2D UI in an empty scene and created a label.
You can see the issue I have in the attachment. The lines are going up! It only happens with dynamic fonts. I tried a whole ton of different dynamic fonts and its all the same. Never have a problem with bit mapped fonts.