I would guess this to be a common metal characteristic and not a defect in the razor as far as the manufacturing process and the metal used goes. I have a bunch of razors that may only get used once or twice a year. Usually on Father's day we go through the collection to inspect the razors for rust or other issues. Each time we inspect them there are a few that show chipping on the edge that I know wasn't there the last time I used it. This is more noticeable when finding vintage razors that have not been used in decades or more.

My educated guess is that the chipping is due to residual stress in the metal that is causing cracks along the edge (which is very thin) and eventually the metal chip falls away. There are ways to reduce the risk of this with a double draw of the metal after heat treatment. Cryogenic temping is also an option. These process added cost to the razor.

Stress in metal after heat treating is a known characteristic of the metals used. There is no way to guarantee the edge will not chip. Other conditions that cause stress in metals, just to mention a few, are sudden changes in temperature, cutting the metal in any manor including honing and external forces. The effects of the stress are noticed quicker if the stress is only placed on one side of the object like leaving the metal on a flat surface in direct sun light only on one side, machining only one side of the metal.

Get 'er honed again and see if the edge will last a bit longer this time. Good luck.