LG G3 owners on Sprint, you should be getting a new over-the-air update in the next few days. Don't get too excited, it's not a new version of Android - you should have gotten Lollipop 5.0 sometime back in February. Nope, this update does one thing and one thing only: enable factory reset protection, a 5.0 feature that was left out of LG's updated build for some reason.
The new version is LS990ZVA. Sprint doesn't say how big the update is in the official changelog, but for just one change it shouldn't be very substantial. Remember that after the 5.0 upgrade, any changes to your phone's system partition will result in a failed update flash.