Open fontanel in 10 week old kitten

We are in the process of adopting an exotic shorthair kitten. The breeder contacted us this evening and stated that our boy was vet checked this past week and has an open fontanel. It hasn't closed yet like the others in the litter. She stated that she knows this is common in this breed with large domed heads but she wanted to let us know. She said that he appears healthy otherwise and that her vet isn't concerned about it as it should close over time. Should we be worried? We're waiting for our vet to call us back. Thank you so much!

I had never heard of it maybe one of the breeders on the board has and will chime in.  I am just guessing but is it kind of like a baby's soft spot on the head?

My chihuahua has an open fontanel, it is pretty standard for the breed, her's is about the size of a nickel though as she also has hydrocephalus, if she bumps her head it can throw her into seizures so that is something to consider while and if it closes all the way.  Did the breeder say how big it is?  I have worked for  vet for 20+ years and have only seen 1 cat with an open fontanel so it is not all that common.  I hope some of the breeders will chime in who may have more experience with it in cats.

Thank you both for responding. Yes, it's the same as a baby's soft spot. My vet isn't familiar with this breed but she said it was common in chihuahua. The breeder never mentioned hydrocephalus or how large it was. I was wanting to compile a list of questions to ask when I respond back to her. I know that it sounds crazy but we've already bonded with this little guy. We have watched him grow via photos & video and we've got everything ready to bring him home which is supposed to be next week.