start period before take inactive pill!

I been take quasense for the last 2 and 1/2 year. My period always start 3-4 day after i take the inactive pill. This month my period start 1 day before i take the inactive pill I wonder if this is normal or not. I did not missing any pill for the last 3 months, however, i do take 1-2 hours late some night. Does anybody in here now about this, please let me know if this is normal. thank your very much!