Starting period AFTER placebo pills. Strange?

I've been on Yasmin now for 6 months. And every month I start my period usually on the last placebo pill OR the FIRST active pill of my new pack. Is this at all strange? Could that affect its well....effectiveness? I'm not worried about being pregnant, (you have to have for that hahaha) its been awhile for that to have happened. Just wondering if this is weird or happens to anyone else. Thanks!