rake doc:rails aborts due to denied permission

I issue the following commands:

rails new dummy_app
cd dummy_app
rake doc:rails

When issuing the last command I notice that rake aborts due to denied permissions. See below.

rm -r doc/api
Parsing sources…
100% [485/485] /opt/local/lib/ruby/gems/1.8/gems/railties-3.1.3/lib/rails.rb

Generating Darkfish format into /Users/punjabdapunk/Projects/Ruby/dummy_app/doc/api…
rake aborted!
error generating /opt/local/lib/ruby/gems/1_8/gems/actionmailer-3_1_3/MIT-LICENSE.html: Permission denied – /opt/local/lib/ruby/gems/1_8/gems/actionmailer-3_1_3/MIT-LICENSE.html (Errno::EACCES)

Tasks: TOP => doc:rails => doc/api/index.html
(See full trace by running task with—trace)

Performing ls -la /opt/local/lib/ruby/gems/1_8/gems/actionmailer-3_1_3/MIT-LICENSE.html produces:

-rw-r–r-- 1 root admin 92997 27 Nov 23:17 /opt/local/lib/ruby/gems/1_8/gems/actionmailer-3_1_3/MIT-LICENSE.html

Is this normal behavior? I’ve googled and searched forums but to no avail.

I’m a noob to all this and am willing to do what is needed to grok this. Can someone point me in the right direction.

(on Mac OS X 10.6)