Help with GNU PGP - no password prompt when sending e-mails

[Gold IsMoney]

Hello everyone - I am using the following:

OS: windows 7 / 64-bit
E-mail client: Thunderbird3.1.6
GnuPG v1.4.10 (MingW32)
and Enigmail 1.1.2

My problem is that when I send encrypted e-mails, I never receive a
password prompt for the e-mail.  I do receive the password prompt when
actually opening up e-mails (received, or sent, or saved in some folder,
etc.) and mine is set up to remember the password for x number of
minutes, and that feature works fine.

The issue is obvious - if it doesn't ask me for my password when sending
e-mails, it means that anyone with access to my pc can go into
Thunderbird and send encrypted e-mails, using my identity.  Is this a
bug, or is there some configuration somewhere that I need to change?