Strange line on egg

[emcgowy]

Looking for advice - since its been quite hot in Massachusetts over the past few weeks our egg production has dropped but one of our girls (2 years old) has been laying eggs with this line on the shell. The shell quality seems good. Everyone seems healthy. They are on a layer pelleted feed with free range a couple times a week and oyster shell available (arguably less than I probably should). The line is different lengths on each shell. Any thoughts? Anyway I could change/improve husbandry? Thanks in advance!

 

[sourland]

Slight glitch in the reproductive tract - generally it resolves on its own. More common at the beginning or end of a laying cycle.