My iPhone 7 Plus was my daily driver until my iPhone X arrived November 3rd. I did my migration and eventually wiped my old iPhone 7 Plus (and deactivated Find my iPhone) before charging it up for the last time, and placing it back in its original box.
This morning, I opened the phone up to update its software before selling it, and somehow it now has been activation locked by an Apple ID that I have never seen before. I have no idea who could have done this, as the iPhone has been sitting in its box, in a storage box, untouched for almost a month.
I'm taking it to Apple today to have the Activation Lock removed, but I want to know if anyone else has either heard of this happening (and how?) and if not, theories as to why this might have happened?
[doublepost=1513096277][/doublepost]Side note:
If this ever happens to you, you will need to take your iPhone to an Apple Store (ask to speak with a Manager) along with your original proof of purchase and some form of government-issued photo ID.
No appointment necessary, although if you have one, they will greatly appreciate you for having one. If going to an Apple Store isn't an option for you (distance, time, or other reasons), you can call 1-800-APL-CARE, and they can open an investigation over the phone. You will still need to provide the same proof as in the retail store, however instead of getting this fixed in 20 minutes, over-the-phone support for Activation Lock issues can take 7 business days.

This morning, I opened the phone up to update its software before selling it, and somehow it now has been activation locked by an Apple ID that I have never seen before. I have no idea who could have done this, as the iPhone has been sitting in its box, in a storage box, untouched for almost a month.
I'm taking it to Apple today to have the Activation Lock removed, but I want to know if anyone else has either heard of this happening (and how?) and if not, theories as to why this might have happened?
[doublepost=1513096277][/doublepost]Side note:
If this ever happens to you, you will need to take your iPhone to an Apple Store (ask to speak with a Manager) along with your original proof of purchase and some form of government-issued photo ID.
No appointment necessary, although if you have one, they will greatly appreciate you for having one. If going to an Apple Store isn't an option for you (distance, time, or other reasons), you can call 1-800-APL-CARE, and they can open an investigation over the phone. You will still need to provide the same proof as in the retail store, however instead of getting this fixed in 20 minutes, over-the-phone support for Activation Lock issues can take 7 business days.