When a dimension's text doesn't fit between the extension lines, a popular option is to "move text with leader". To match the other leaders, though, this text can be vertically centered on the leader. (Default behavior places the text over a line.) To quickly change this, simply select the dimension, then right-click and select "Dim text position-->Centered" from the menu. You can change this setting from Properties too, but only if you haven't grip-moved the text to another location. Once it's moved away from the default, the right-click menu is the quickest way to change it.