I would not be concerned. After the winter break, or at the start of their egg-layer life, they just need some "dry-runs" to figure things out (again). I have rough-shelled, thin-shelled, double-yolk, yolkless and sunnyside-up eggs every spring. Usually it is all back to normal in a few weeks.I know, makes me a little nervous, one was long and skinny, I hope they aren’t setting up for reproductive issues.