So, I'm in a sketch, and I draw a vertical line a random distance from a vertical edge on the model.  When I use the smart dimension tool to display the distance between them, if I drag the cursor to the left, I get an accurate distance, but if I drag the cursor to the right, the distance doubles, and the leader arrow no longer is anywhere near the vertical surface.  What is this "feature" called, and how how how do I turn it the heck off?  I have absolutely no need of distance doubling, or radius vs diameter measurements, if that's the case...