Comscore measures installed base, not sales. In the same period BB lost 600,00 users WP added 143,000. Because both platforms may be losing legacy users (Blackberry BB7 users and WP old Windows Mobile users) its difficult to deduce sales figures from this, but it certainly does not look like BB is outselling WP in the USA.
BTW, the 40 days of BB Z10 sales excuse is pretty poor. Was there no pent up demand at all?