Nexplanon

Ladies,
I've been on the Nexplanon for just a little over a year now. When I first got it, I had a period for about a month and then nothing at all beyond that. Now, I just had my first period since then. (Consequently I've also recently had sex for the first time since this new birth control change.)
I read somewhere that the closer some women get to their 2.5 year mark their periods will start up again because the hormones left will concentrate on stopping the ovulation not the menstrating... but I'm barely beyond a year in.
Any thoughts? Does this seem "normal" for the implant? Could this be a product of the recent sexual activity?