Hen laying cracked eggs

[kinnafinn35]

Has anyone seen this before? We have gotten at least 2 of these in the last 1-2 weeks. It also seems to be the hen that went from laying darker brown eggs to light pink, almost white eggs. The crack goes pretty much all the way around both, with one extra cracked spot on the side as you can see to the left of each egg in this picture. The egg also bulges out more where the "extra cracking" is...It's hard to get a god picture of these!!
They all have access to free choice oyster shells and eat a layer feed. Any ideas?

 

[Judy]

Here you go:

http://www.thepoultrysite.com/publications/1/egg-quality-handbook/14/hairline-cracks