The pill-no period

I've been on the pill for over a year and my periods have been regular and consistent. My pill week starts on Sunday my period comes Wednesday-Saturday. Last month it was Friday-Saturday. It was only one day, weird. Well this month I haven't had one at all and last night I start my new pack. Has anyone else had this happen? I took a pregnancy test to be safe and it says I'm not pregnant, so I'm just wondering if this is a common occurrence with the pill.