Was it a first egg? I had one like that several weeks ago but it was the first egg of a young pullet. I have not had another one. Just as a precaution I bought some Oyster shells from Tractor Supply and made them available for the hens.
Ours have just started laying. We have gotten about a dozen perfect beautiful eggs. We also have gotten one with a very thin shell and two shell-less eggs. We did add a little oyster shell just in case, but it seems to be the consensus that it is pretty normal when they first start laying. I just make sure to check for eggs at least twice a day because I don't want them to get a taste of one.