[Enigmail] Enigmail, PGP, Gmail and decryption

[Giano]

Hi guys. I'm a newbie and I've just installed and configured
Enigmail+gpg on my pc. It works really fine, both signing and
encrypting, but I found a very strange thing.
I use Enigmail on my Gmail account via IMAP, and I sent an encrypted
email to my girlfriend. Then I explored "sent messages" and... I was
able to decrypt the sent message using my key!!
How is it possibile? There should be some misunderstanding...
Thank you for the help! Bye!
-- 
~~~~~ GIANO ~~~~~

E-mail:  alex89.ficus at gmail.com
Website: http://gianopage.altervista.org/
Skype:   alex89.ficus
Twitter: http://twitter.com/giano89

"Per una persona ottimista, il bicchiere e' pieno a meta'. Per una
persona pessimista, e' vuoto a meta'. Per l'ingegnere, e' due volte piu'
grande del necessario."

-----PGP KEY FINGERPRINT-----
7B19 3021 2218 5AE5 F90D  895F 64E3 5598 5920 9728