Sorry for the doubble post, but you can use set -u instead of using a timer to remove the variable.
/help /set
Also; this is how id code it:
on *:TEXT:*:*: {
if ($highlight($1-)) {
if (($version == 6.31) && (!%tip. [ $+ [ $nick ] ])) {
noop $tip(\'Tray Tip\', $nick , $nick just said your name in $chan with the following message:, 10)
noop $tip(\'Tray Tip\', Message, $1-, 10)
beep
set -u20 %tip. [ $+ [ $nick ] ] true
}
else {
beep
}
}
}