Tolerances of stock bed?

I see this wave in my Heightmap. The Corners looking ok for me for now. I checked all rails and refastened them from one to the other side. No change 😦 It looks like the bed has this wave itself. I checked the bed like this. What are the default tolerances which would be ok for the bed? Is this a reason to ask for an exchange? Or should i proceed with heater and magnet etc?