Why does the Dumper module place parens around the assignment of its settings hash?

Having read this question and this question on the differences between my $var and my ($var), I was still unable to see why the Data::Dumper module uses parens in the following excerpt from its code. None of the differences described in the answers to those questions seem to apply here.

  my($s) = {
        level      => 0,           # current recursive depth
        indent     => $Indent,     # various styles of indenting
        # a bunch of other settings removed for brevity's sake
        deparse    => $Deparse,    # use B::Deparse for coderefs
        noseen     => $Sparseseen, # do not populate the seen hash unless necessary
       };

I tested it out in a small script and I can't perceive any difference between declaring this as my ($s) or as my $s. In both cases it is a scalar reference to a hash, so far as I can tell.

Am I missing something?