yes sounds like a stupid question

but here goes..
on one of my mountain bikes with a solid axle, while repacking the rear hub i rolled the rear axle on a flat surface to see if it was straight.. seemed to be slightly bent.
i went to a local shop, the guy brought out the one solid axle they had left.. i checked it.. slightly bent as well.
went to a 2nd bike shop.. looked at another rear axle.. also had a slight bend. what's going on here?
is this slight bend acceptable? is quality control that bad? or is it this a normal/acceptable deviation from 100% straight? do i need to find some better shops LOL.
i'm concerned since i don't want to wear out the hub running on a bent axle.. but hey.. if a small bend is okay.. then its just less for me to worry about.
thanks for reading