One Day Period on BC

I have been on BC for about 5 years now. For the past year my periods have gotten lighter and shorter. For example, I start on Wed and am over by Friday with some spotting on Saturday. Well this month I started spotting brown/dead blood on Wed, and on Thursday I put a bleed normal through one tampon and replaced it. After checking the tampon hours later, only a few spots. And today (Friday) Nothing! I spotted a little this morning but thats it! What does this mean? Is it normal for someone who has been on BC for a long time?