Late period on birth control?

I'm currently a day late while on Yasmin. However its only my 4th month on the pill. I'm a little worried, but im wondering if its maybe because instead of finishing the full week of inactive pills, last night I started a new pack so that I could change the day of the week I got my period in future months. I was supposed to get my period late last night/early this morning, but I still haven't gotten a period (I usually get my period on the fourth day of the inactive pill, today is the 4th day.) Could it be that I just screwed up my hormones by not finishing the pack and starting a new one? I haven't had any pregnancy symptoms, so I'm sure its that, I think that's what happened last time I took my active pills early. Anyone have an experience like this before? Or should I start to worry?