Weird shaped eggs

How old is your girl??
Mine were doing it not long ago and I was told it's just what happens as a hen gets older. Thats why battery hens are slaughtered at 18 months, because the shops wont buy wonky eggs, they have to be perfect. After 18 months the shell quality drops off slightly...the egg itself is fine, but doesnt look pretty on the shelves.
My chickens are ex-batts, and their eggs have always tasted lovely...I've had some funny looking ones though
If she's a young chicken...stress can cause rippled shells, if she's frightened while actually laying, the tightening of the muscles when she jumps can cause funny shells. If she's a flighty bird, then it may be that. Thats was off a programme I watched from the 'Happy Eggs' producers, so how true it is, I dont know??