I recently bought my first brand new cast iron skillet. After I seasoned it and used it a few times I put it away in my cabinet and it scratched the shelf (cheap grade pressed wood). I felt the bottom of the pan and there is a sharp bump sticking out of the bottom. Is this normal and will it go away? Should I return the skillet? My parents and grandparents cast iron pans are all smooth but also have many years of use so I have never seen this before.