Phantom Account login

[den3 0]

I have been receiving notification emails that "Someone has logged on the device using the Phantom Account." However, the device is not lost or missing ... I am using it and logged-on as me (not mistakenly logged-on as the Phantom Account) I have cleared the status on my account but want to know what triggers these notifications - this has happened a few times over the last couple of months. Is there some other security issue to investigate?