I recently acquired a vintage 1920s Wagner DO which is beautiful, but the bottom is a bit warped (not too much of a problem on my gas stove). The bottom interior has some wavy lines, and I'm curious if these are a result of the warping, and/or if I should expect it to crack in these spots- i.e. are these lines a weakness? It is not yet cracked, but I'd like to avoid that happening if possible. Any recs or info are appreciated.