Restarting period with Mirena

Gina
Go Mirena installed March 2013. Period stopped immediately and has been absent for nearly 3 years. Last month I started spotting for a few days, didn't think anything of it. This month I have a super light flow period. I was wondering if anyone else has had their period restart while on Mirena. I suspect it's because the device is over its half life and is releasing fewer hormones.