Are u kidding me? If that's the case then alot of sites should change design because there's some similarity. A dark header that runs across the page is hardly enough to consider a rip. Your navigation isn't in yet so you can deviate with that.

I don't see similarity, I don't see it as a rip but for safety, you should start over.

Besides, Site5 seems to be changing site design like clothing. I really don't know what's up with that. Only goes to show that they're a young company.