Why is rvm re-ordering my $PATH?

-why?.txt

Why is rvm re-ordering my $PATH?

I can understand it placing its own dirs
on the front of the path... but why have
items 1-7 been shuffled below items 8-13?

(And no, I don't know why the /opt/local
 dirs are there both with and without the
 trailing slash.  I'll clean that up.)

shell.txt

Last login: Wed Nov  4 11:44:38 on ttys015
== (nick@caladan)   [Wed Nov 04]-(11:46:12) ==
~ $ echo $PATH | awk -F : '{print "PATH is set to"} {for (i=1;i<=NF;i++) {print "["i"]",$i}}'
PATH is set to
[1] /Users/nick/.gem/bin
[2] /Users/nick/.gem/ruby/1.8/bin
[3] /Users/nick/bin
[4] /opt/local/sbin/
[5] /opt/local/bin/
[6] /opt/local/bin
[7] /opt/local/sbin
[8] /usr/bin
[9] /bin
[10] /usr/sbin
[11] /sbin
[12] /usr/local/bin
[13] /usr/X11/bin
== (nick@caladan)   [Wed Nov 04]-(11:46:15) ==
~ $ rvm use 1.8.6
== (nick@caladan)   [Wed Nov 04]-(11:46:18) ==
~ $ echo $PATH | awk -F : '{print "PATH is set to"} {for (i=1;i<=NF;i++) {print "["i"]",$i}}'
PATH is set to
[1] /Users/nick/.rvm/ruby-1.8.6-p383/bin
[2] /Users/nick/.rvm/gems/ruby/1.8.6/bin
[3] /Users/nick/.rvm/bin
[4] /usr/bin
[5] /bin
[6] /usr/sbin
[7] /sbin
[8] /usr/local/bin
[9] /usr/X11/bin
[10] /Users/nick/.gem/bin
[11] /Users/nick/.gem/ruby/1.8/bin
[12] /Users/nick/bin
[13] /opt/local/sbin/
[14] /opt/local/bin/
[15] /opt/local/bin
[16] /opt/local/sbin
== (nick@caladan)   [Wed Nov 04]-(11:46:19) ==
~ $ gem list rvm

*** LOCAL GEMS ***

rvm (0.0.74, 0.0.37)
== (nick@caladan)   [Wed Nov 04]-(11:46:29) ==
~ $