shouldn't /+(??) capture 2 letter files only?

[gregrwm]

i wanted to move a bunch of files & directories, all except a certain
few, so i figured i'd use !(this|or|that).  so first i looked to see
if +(this|or|that) isolated what i expected.  well perhaps i don't
understand what it's supposed to do..  shouldn't /+(??) capture 2
letter files only?

$  echo /+(????)
/boot /home /proc /root /sbin
$  echo /+(???)
/bin /dev /etc /lib /mnt /opt /run /srv /sys /tmp /usr /var
$  echo /+(??)
/b1 /boot /c6 /e1 /home /initrd.img /lost+found /nu /pl /pm /proc /px
/ql /root /sbin

$  uname -a;apt-cache policy bash
Linux phovd 3.2.0-23-generic #36-Ubuntu SMP Tue Apr 10 20:41:14 UTC
2012 i686 athlon i386 GNU/Linux
bash:
  Installed: 4.2-2ubuntu2
  Candidate: 4.2-2ubuntu2
  Version table:
 *** 4.2-2ubuntu2 0
        500 http://us.archive.ubuntu.com/ubuntu/ precise/main i386 Packages
        100 /var/lib/dpkg/status