Preview: Let go of that file!

This happens all too often:

1. I receive a PDF file and open it in the Mac OS X Preview app.
2. I read the document, then decide I no longer need it. I close the Preview window (but do not exit the Preview app).
3. I move the PDF file to the trash.
4. I empty the trash.
5. I see this, and smack my forehead:

See what I did wrong? I forgot to quit the Preview app. You see, Preview likes to hang on to files it has opened, even after they've been closed. Silly user! Quit the Preview app and then empty the trash.

Apple, please fix that.

(No, I will never, ever, ever use Adobe Acrobat instead. I don't have the time to create all the Please Fix That posts for that app.)

Observed as recently as Mac OS X Lion 10.7.4.