Mini pill

I've been on the mini pill for about a year now, I've never had a problem with anything then all of a sudden if I miss my pill or take it later than I normally do i start to bleed it stops usually within the next 24 hours once I've taken my pill. I'm worried because my period has always been on time without a problem with no extra bleeding and it's always the same. Along with e everything I've said the bleeding can vary from brown to bright red. Sorry about the t.m.i guys. Just wondering if anyone knows anything about this or has experienced it?