This doesn't happen for me using a default install of 2013-02-09-wheezy-raspbian, plus apt-get update/upgrade.
If I understand the script correctly it seems to be triggered by /usr/bin/pistore-desktop checking whether sudo is able to get elevated privilege without prompting for a password. If a password is needed it uses an Lxterminal to provide the prompting mechanism. Otherwise it just brings up the pistore window alone.
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