a newbie question on passphrase to decrypt an encrypted file

[Dongping Deng]

I installed gpg (win32) on my machine running NT. I generated my key with my
passphrase. When I encrypted a file, it asked me for the passphrase. But
when I decrypted it, it didn't ask me for the passphrase at all. This sounds
scary to me. I can't seem to find the answer from various documents. Don't
you have to type in your passphrase to decrypt a file?

Thanks!

dp deng
dp@asimba.com