Sounds like this is just narrowing down the old requirement which was that you had to have your registration # on the outside of the aircraft -or- accessible on the inside such as in the battery compartment.
Now having it in the battery compartment isn't sufficient; it must be on the outside.
I wasn't aware of this recent change. Glad I went ahead and put the # on the outside of my 2nd copter a few days ago. I almost put it inside.
I put mine on the outside as well, just wanted it to look more like a real flying machine. Soon we will all be hunted down and burned at the stake anyway, so it won't matter.