it is most likely not a calcium problem...sometimes weid eggs happen. I had a chicken who would lay an egg with no shell once a month...and all her other eggs were thick-shelled. for calcium defficiency look for thin brittle shells. shape is difficult to say...when my hens first start up for the year someimtes i get eggs with a swirly end...looks like they came out of a paly-doh squisher lol. They should be fine, would think.
