Nothing in the code you show does anything that would give $! a meaningful value. The value $! actually has at the moment the code shown is executed was either set in some previous operation that gave $! a meaningful value (update: see this), or else it's the value $! happened to have at program startup (update: see this), i.e., random. Either way, its value is meaningless.
Update: Consider this code:
c:\@Work\Perl\monks>perl -wMstrict -le
"my $year = 987;
$! = 0;
if ($year !~ /\d{4}/) { die qq{Idiot!, use 4 digit year. Stopped '$!'
+} }
"
Idiot!, use 4 digit year. Stopped '' at -e line 1.
Now try assigning different values (1, 2, 3, ...) to
$! and see what messages you get. The messages you're seeing in your posted code are just cruft.
Give a man a fish: <%-{-{-{-<