Spotting

So I've had the Mirena IUD for 2 years now and haven't experienced any out of norm issues. I've been regular with my periods, and always get the cramps, bloating, and other symptoms right before never anything abnormal but 2 days ago I thought I was starting AF early since I started spotting but had no cramps, bloating, etc but it was so light and it's gone now. I'm not due for my period for another week and like I said I'm I've been on Mirena. Any thoughts?