Last week I pressure canned some dry beans, I didn't have any problems with the canning process, However ... when I opened the canner the seal fell out. It was wavy and standing on the outer edge. I couldn't make it lay flat. I am curious as to what made it do that. I tossed it up on the counter so I would have it handy when I go to town. Today I noticed it is laying nice and flat. Do I need to replace it? It is an old presto canner I have used for years. I have never seen anything like this. Thanks for any insite you care to share.