access modifiers for type members

Given this trait, with a private type member:

scala> trait X { private[this] type A = Int; def a: A = 1 }
defined trait X

The access restrictions correctly prevent me from accessing the type
member from outside of `x`.

scala> type xA = x.A
:10: error: type A is not a member of java.lang.Object with X
type xA = x.A
^
scala> val x = new X {}
x: java.lang.Object with X = $anon$1@58bf7b3e

scala> x.a
res6: Int = 1

But I can see the type in the eta-expanded signature here:

scala> x.a _
res7: () => x.A =

Not sure if this is a problem, it just strikes me as a bit odd to
allow private type members to appear in public signatures, by contrast
with the way private template definitions are handled.

scala> trait X { private[this] trait A; def a: A = null }
:8: error: private trait A escapes its defining scope as
part of type X.this.A
trait X { private[this] trait A; def a: A = null }
^
Any insights into the distinction?

Thanks,

-jason