It has nothing to do with us, rather it is paying homage to their 96/97 kit. Their new one is such an ugly and yucky jersey, it doesn't even come close to the awesomeness of our Blaugrana design.
Could be because of he flag of Milan, or it could be a retro design. I'm not sure if the original kits had it on because of St. Ambrose or because the club was founded by English expats. Maybe both.