Have you ever run into this where your temporary dimensions just look different. This happened today to a user at our firm and after some investigation I figured out what was going on... In this case, the arrowheads were huge as shown below.
He're how they should have looked.
To fix the problem, go to the Settings Pulldown, then Annotations, then select Arrowheads.
You'll notice that when you open the dialog box, Type is blank. What ever Type Parameters are set here are used by the Temporary dimensions. I haven't yet investigated what else references this in Revit, but the temporary dimension sure do... In our case, the user made some changes here instead of duplicating an existing type for their unique situation. Once we set the parameters back to their orignial settings - all is good!