What regenerates files in ~/.gnupg?

[Zembower, Kevin]

What's automatically regenerating the files in my ~/.gnupg/ directory,
using the Ubuntu 8.04 system:
kevinz at kevinz-laptop:~$ date;rm .gnupg/*;sleep 10; ls -l .gnupg/*;date
Mon Jun 23 12:30:38 EDT 2008
-rw------- 1 kevinz kevinz  0 2008-06-23 12:30 .gnupg/pubring.gpg
-rw------- 1 kevinz kevinz  0 2008-06-23 12:30 .gnupg/secring.gpg
-rw------- 1 kevinz kevinz 40 2008-06-23 12:30 .gnupg/trustdb.gpg
Mon Jun 23 12:30:48 EDT 2008
kevinz at kevinz-laptop:~$ 

This really bit me recently, when, as a newbie to gpg, I copied my keys
from another system to a USB memory stick, then copied them to the
kevinz-laptop system to learn how to use encryption with Evolution,
added a new key for private use, uploaded it to keyservers, then tried
to move the files back to my USB stick. When I saw the files
regenerated, I thought I had made a mistake with my 'mv' command, so
without looking at the timestamps or sizes of the file, just repeated
the 'mv' command, with the result of wiping out the new key I generated.

Thanks for your help understanding this issue.

-Kevin