[coronabarb]

Agree with above, the lids should 'ping' and dimple inwards at some point after removing from water bath. An upward bulge at all is indicative of not a good enough vacuum seal and the food is not safe to store at room temp. It can be from not leaving enough headspace or tightening lids too much. You can reprocess or refrigerate or freeze. Make sure you are using only approved canning jars, lids and rings and nothing with rust...always use new lids. Don't use leftover store product jars (like spaghetti sauce jars). Follow approved directions such as local extension or Ball Blue Book. Next time, see if you can take a picture. :-D