I was checking the level & pitch on my 60" deck and noticed the replacement blades were not consistent with each other. In other words, when set on a flat surface or against a straight edge, some were flat, some were bowed up. Now, all I had were slightly to moderately used. The blades are Oregon #91-253 and their Fusion #491-506. I have never hit anything substantial, I'm only mowing my property. I don't currently have any new blades to check. Some of these blades may have less than 4 hours on them. Anyway, just wondering if anyone has ever checked new blades and noticed this? I happen to notice about 1/8" difference in the center blade and the left and right blades, due to the center blade being slightly bowed up and the left and right blade being flat. I checked at the point were the blades passed by each other. Thanks for any insight on this subject.