strange spotting

So I had my period end on Christmas Day, and my upcoming period is scheduled for the 18th, on the 11th I had some faint pink blood discharge, very light, and it was once and it wiped away and never came back, it has been 4 days and I have no boob pain and no blood and no cramps. My period starts in 4 days (or should) but I was wondering what that could have been!? Any thoughts? (I have stopped taking birth control and my period was early last month by six days, and I am not using protection)