That is called a 'vaulted skull'. Some silkies hatch with it and some do not. People who show silkies want a vaulted skull because it makes the crest look bigger and 'poofier'. Show us pics of your babies! We LOVE baby pics!!
I was also told to be careful about the silkies skull or something to that sort. As it has an open plate and can get brain damage from being pecked in the right spot. I think thats what it was. I don't have any challenged silkies yet so maybe they weren't pecked.
Yes, be careful with chicks with vaulted skulls. I hatched a vaulted skull baby from one of my eggs, and starting at about 2 weeks old, she will stop and shake her head around. I think she bumped her head when she was little and it gave her some brain damage. But other than that, she is a happy little thing.
Vaulted skulls are common, and usually purposely bred for in the US. There has been some controversy over it lately, and some breeders are getting away from it. Its a personal choice whether or not you would like it in your lines.
The only special care they need is to make sure nothing hits their head seriously hard while they are young. (IE: no pecking by older birds)