I have a full RH6.1 install. As a user I run "screen". I notice I get allocated "/dev/ttya0", and the permissions are -rw-rw-rw-, owned by root. This is very dangerous! It looks like screen has failed to use /dev/pts/0 (UNIX98 pty support). xterm and rxvt handle pty's correctly, screen should mimic their behaviour. PS. I like screen's usage of user-private .screen directories, much better.
Fixed in screen-3.9.4-3, in the errata. (As an aside, using the user private .screen directories, while more secure, breaks on Linux<->non-Linux NFS. :( )