It's not paranoid but good practice, because (as ELISHEVA pointed out below) a DESTROY method can accidentally reset the global $@ variable, as this small piece of code demonstrates:

use strict;
use warnings;
use Data::Dumper;

sub DESTROY { eval { 1 } }

eval {
    my $obj = bless {};
    die "wrong";
};

print Dumper $@;
__END__
$VAR1 = '';
[download]

The correct solution is to localize $@ in the DESTROY sub, but you can't always rely on third-party modules to do such things correctly.