Hi, @sc0tte. Welcome to the community! This doesn’t happen very often but I have experienced this as well. If there is an interruption in power like a small intermittent or brownout this will cause the camera to power cycle and turn on. This is the main cause for the camera to turn on by itself. You can just turn the camera back off through the app. If the camera continues turn back on again, you will need to look into other possible causes like someone you may have shared the camera/account with. 
Edit: Here is another possibility posted here: