"Oh lol, it's below da 3DS, teh DOOOOMESZ, I say!"
I don't know if anyone seriously expected the vita to outsell the 3DS. It just won't happen. But if it manages to significantly increase its weekly numbers, the Vita should be perfectly fine. I wouldn't worry too much.
Official member of VGC's Nintendo family, approved by the one and only RolStoppable. I feel honored.