Nah it was just what the title creator did to make it look cool, GRRM has specific called it as an alternative earth
"In the beginning, it was very simple, nothing animating and everything very flat. One of the things we realized early on was that you couldn’t really tilt the camera up very far because it raised the question, what’s beyond the map? (…) The fact that I wanted to be able to move the camera anywhere led us to the fact that this whole world had to exist on the inside of a sphere, which took us a while to figure out. (…) If you have a whole world inside a sphere, what would be in the middle of that sphere? The sun! Or whatever the light source of this world is."
GRRM
"This may be a silly question, but: When you think of the world you’ve created, where seasons last for years, where is it? It is another planet?
It’s what Tolkien wrote was “the secondary world.” It’s not another planet. It’s Earth. But it’s not our Earth. If you wanted to do a science fiction approach, you could call it an alternate world, but that sounds too science fictional. Tolkien really pioneered that with Middle Earth. He put in some vague things about tying it to our past, but that doesn’t really hold up. I have people constantly writing me with science fiction theories about the seasons — “It’s a double star system with a black dwarf and that would explain–” It’s fantasy, man, it’s magic."
"3) Is your world round. I mean if Dany traveled far enough east couldnt she come to the other side of westeros?
Yes, the world is round. Might be a little larger than ours, though. I was thinking more like Vance's Big Planet.... but don't hold me to that."