Could your test be failing due to a timing issue, here, due to this param?
It doesn't really look like it because it does appear as though you're handling and sending in the $age param correctly, but printing out the variables wouldn't hurt (ie. my $x = -M $file; print "$x: $age\n";) to see what's going on there for real.
Can you reproduce it on a local machine at all?
You could try adding a delay of a second after the cleanup() routine (eg: sleep 1;), and before the file-exists test. Perhaps the full cleanup of the file isn't quite complete in some systems before checking if the file is really gone.