This week brought the unexpected closing of the Pack-‘n’-Ship store next to 7 Locks Barber at Potomac Woods Plaza — one of those longtime neighborhood businesses that you don’t appreciate until it’s gone. For Amazon Primers and other heavy users of UPS, the next-closest drop-off locations include Wintergreen Plaza on Rockville Pike, White Flint Plaza on Nicholson Lane, Westlake Crossing outside Westfield Montgomery Mall and the Potomac Promenade shopping center on Falls Road.