Why is a rewrite rule in wordpress prevent pagination?

I changed:

add_rewrite_rule('^brand-list/([^/]*)/([^/]*)/page/([0-9]+)?','index.php?pagename=brand-list&brand=$matches[1]&section=$matches[2]&paged=$matches[3]','top');

to:

add_rewrite_rule('^brand-list/([^/]*)/([^/]*)/page/?([0-9]{1,})/?$','index.php?pagename=brand-list&brand=$matches[1]&section=$matches[2]&paged=$matches[3]','top');

Note the difference is /page/([0-9]+)? is now /page/?([0-9]{1,})/?$

seems to be working now.