What Causes Delayed Periods With Light Spotting?

I had my last actual period on november 11 it lasted about a week thats a little long but not nothing to worry me. I didnt have a period at all during the month of december and i started on Jan 7 about 2 A.M i thought ok im starting my period but i put a pad on and at 7 that morning there was nothing on it and i havnt seen anything else since then. Is that a sign of anything maybe?