If you feel like you want to take this up with Facebook, you do that.
Otherwise it is now time to change your facebook password.
I was wondering if somebody would be able to help me figure this out. I just received a email stating that I had a Facebook login alert that was from another Android phone that was not mine and I was wondering if there's a way that I could somehow use an IP address or some other way to determine maybe we're about this person lives because I sort of have an idea. Or if there's a way that I can find out there email or their IP address that they used on their phone or possibly I could ping to it if that's a possibility