The important thing is that the blade is square, through its entire range of motion, not just when it is sitting still. The DeWalt, as well as most other saws, cuts with a slight oscillating action. It's only a few thousands of an inch, but it means that most of the time, when the saw is not running, the blade will be slightly out of square, front to back.
To check if your saw is cutting evenly, with no over or under cut; take a thick piece of wood, the thicker the better and just kiss it with the running blade to make a shallow kerf in one edge. Examine the kerf to see if it is deeper on the top or the bottom. If it is, then there may be some adjustment that needs made. I believe that Rick Hutcheson's website has info on some of the methods people have used to minimize the variance. Under normal circumstances, the saw should make an even kerf and no adjustment should be necessary.