Grey arrow (location service icon) next to "Find my iphone"?

Hi,

I have an iphone X with IOS 11.2.1.

I've learned that if you go to settings -> privacy -> location services -> system services, you can tell if certain system apps used your location recently, with a purple arrow next to the item's being "used very recently", and a grey arrow being "used in the past 24 hours".

Despite that I haven't even opened the app "Find my iphone" in at least a week, I find that there is a grey arrow next to "Find my iphone", and it hasn't gone away for a couple of days now. Does this mean someone else is using my login ID and password to track my location all this time? Or could the app itself cause this grey arrow to stay? (maybe it's accessing my location on it's own from time to time?)

I understand changing the password is a easy fix for this potential problem, but I do not want to do that because I just want to figure out if the person I gave my password to was tracking me.

Thanks!

James