A question about grids and measuring

I am new to Librecad (and only a basic understanding of CAD in general) and I'm really enjoying it so far.  I am fairly sure that it will serve my purposes.  As i'm experimenting around, something came up that I was hoping someone could help me with.  In my "current drawing preferences" I set the "main drawing unit" to millimeters.  Then, I set the grid x and y spacing to 1 and 1.  I was thinking that set my grid to be 1mm apart.  I drew a rectangle, snap to grid, 1 x 4 grid spaces.  But then when I took a measurement, snapping to the intersection, it measured 10x40.  What gives?  Am I doing something wrong?  Thanks for any time you care to give my question.

The same thing happens if I choose "auto" for the x and y grid spacing

Erp, I found the problem.  Totally me.  I hadn't zoomed in far enough to reveal the actual grid so I was snapping to the 10mm grid as opposed to the 1mm grid.