GNU Screen on MacOS 10.8 says "Be careful! New screen tonight"

Solution 1:

You are using screen with the option #NETHACK defined.

Nethack is a old text based game with many surprising twists, including dependency on the phase of the moon. If it is full moon the in game were-monsters are stronger.

Screen has an option to translate some of the normal messages into 'nethack-ish' messages. One of the Nethack messages is "Be careful, new moon today". The screen version of that is "Be careful! New screen tonight.")

A list of the messages from the screen source:

#ifdef NETHACK
static struct nlstrans nethacktrans[] = {
{"Cannot lock terminal - fork failed",
     "Cannot fork terminal - lock failed"},
{"Got only %d bytes from %s",
     "You choke on your food: %d bytes from %s"},
{"Copy mode - Column %d Line %d(+%d) (%d,%d)",
    "Welcome to hacker's treasure zoo - Column %d Line %d(+%d) (%d,%d)"},
{"First mark set - Column %d Line %d",
    "You drop a magic marker - Column %d Line %d"},
{"Copy mode aborted",
    "You escaped the dungeon."},
{"Filter removed.",
    "You have a sad feeling for a moment..."},
{"Window %d (%s) killed.",
    "You destroy poor window %d (%s)."},
{"Window %d (%s) is now being monitored for all activity.",
    "You feel like someone is watching you..."},
{"Window %d (%s) is no longer being monitored for activity.",
    "You no longer sense the watcher's presence."},
{"empty buffer",
    "Nothing happens."},
{"switched to audible bell.",
    "Suddenly you can't see your bell!"},
{"switched to visual bell.",
    "Your bell is no longer invisible."},
{"The window is now being monitored for %d sec. silence.",
    "You feel like someone is waiting for %d sec. silence..."},
{"The window is no longer being monitored for silence.",
    "You no longer sense the watcher's silence."},
{"No other window.",
    "You cannot escape from window %d!"},
{"Logfile \"%s\" closed.",
    "You put away your scroll of logging named \"%s\"." },
{"Error opening logfile \"%s\"",
    "You don't seem to have a scroll of logging named \"%s\"."},
{"Creating logfile \"%s\".",
    "You start writing on your scroll of logging named \"%s\"."},
{"Appending to logfile \"%s\".",
    "You add to your scroll of logging named \"%s\"."},
{"Detach aborted.",
    "The blast of disintegration whizzes by you!"},
{"Empty register.",
    "Nothing happens."},
{"[ Passwords don't match - checking turned off ]",
    "[ Passwords don't match - your armor crumbles away ]"},
{"Aborted because of window size change.",
    "KAABLAMM!!!  You triggered a land mine!"},
{"Out of memory.",
    "Who was that Maude person anyway?"},
{"getpwuid() can't identify your account!",
    "An alarm sounds through the dungeon...\nThe Keystone Kops are after you!"},
{"Must be connected to a terminal.",
    "You must play from a terminal."},
{"No Sockets found in %s.\n",
    "This room is empty (%s).\n"},
{"New screen...",
    "Be careful!  New screen tonight."},
{"Child has been stopped, restarting.",
    "You regain consciousness."},
{"There are screens on:",
    "Your inventory:"},
{"There is a screen on:",
    "Your inventory:"},
{"There are several screens on:",
    "Prove thyself worthy or perish:"},
{"There is a suitable screen on:",
    "You see here a good looking screen:"},
{"There are several suitable screens on:",
    "You may wish for a screen, what do you want?"},
{"%d socket%s wiped out.",
    "You hear %d distant explosion%s."},
{"Remove dead screens with 'screen -wipe'.",
    "The dead screen%s touch%s you. Try 'screen -wipe'."},
{"Illegal reattach attempt from terminal %s.",
    "'%s' tries to touch your session, but fails."},
{"Could not write %s",
    "%s is too hard to dig in"},

If you wish to get the normal messages then uncomment #define NETHACK from your profile or recompile screen without support for it.