Welcome to the forum, and congrats on your new bike!
What revs does it sit at when you're at 70mph? And if you can remember, the mpg figure while it's there?
Also a few other bits of info -
What's the mileage? (has it had first service?)
Do you have adequate play in all the Controls (clutch levers, throttle etc)
There are plenty of experienced riders / Ninja 1000 owners on here and I'm sure it'll either be a quick fix or someone on here will tell you it's normal for the bike (as I have figured a lot of things are).
Did you have another bike before this one?
If you've bought direct from dealership I'm sure you will be able to take it back to them to have it checked out.
All the best!