VRF leaking without route-target?

On a N7K, I defined a VRF, lets call it:

vrf context WTF
rd 500:1
address-family ipv4 unicast

There's another VRF, lets call it:

vrf context NotHere
rd 700:1
address-family ipv4 unicast

route-target import 700:1

route-target export 700:1

I built a BGP session that advertised a default route into VRF WTF - and somehow that route appeared in VRF NotHere...

That's not supposed to happen right? Once I defined a junk route-target export within WTF's context, it stopped happening.