Potential bug?

I've just discovered a weird quirk in PHP. I'd first like to check if it is a known bug/weird feature/something else already known. I've not yet tested it much, except I see it doesn't happen on every script, but either of the two results are quite strange to me. Suituation: file myscript.php exists, directory myscript/ does not. If I browse to http://myhost/myscript.php all is well. But http://myhost/myscript/ does return something, where I expect a '404 not found'. Sometimes it just returns myscript.php. BUT sometimes it returns the PHP source (minus PHP comments). Aslo, http://myhost/myscript/anything/anything/bla.bla.bla returns the same. I was running PHP 4.0.4pl1 on RedHat Linux 6.2, kernel 2.4.6. I upgraded to PHP 4.0.6 and still see this behavior. P.S. For the curious I discovered this because a personal site I have uses directory/admin.php for site admin, while another site I am developing at work uses directory/admin/ and I typed the wrong one at home :)