Disclaimer: this bug has been filed in a semi-automated manner.
When emerging the package app-text/libpaper-1.1.24-r1, the following elog messages are displayed:
* run "paperconf -p letter" as root to use letter-pagesizes
* or paperconf with normal user privileges.
Such messages should only be displayed when the package is a new install.
These situations can be checked in the ebuild as follows:
if ! has_version 'app-text/libpaper'; then
See the tracker bug 440214 for more details.