[gentoo-user] Blocked package not installed?!

[Sevak Avakians]

This is weird...
I've:
USE="~x86 nptl threads" emerge glibc --pretend
which gives:
These are the packages that I would merge, in order:

Calculating dependencies ...done!
[blocks B     ] sys-kernel/linux-headers (from pkg sys-kernel/linux26-headers-2.6.8.1-r2)
[ebuild  N    ] sys-kernel/linux-headers-2.4.21-r1
[ebuild  N    ] sys-kernel/linux26-headers-2.6.8.1-r2
[ebuild   R   ] sys-libs/glibc-2.3.4.20040808-r1

But, I've already:
emerge --unmerge linux-headers

And there's no linux26-headers installed on my system:
emerge --unmerge linux26-headers

--- Couldn't find linux26-headers to unmerge.

>>> unmerge: No packages selected for removal.

So, what in the wild, wild, world of sports is goin' on here?!?!