How do you know it's searching for GPS signal? Is there a popup message or an icon in the notification area?
Do you have any apps that may be searching for that signal? Weather widgets and video-streaming apps often request access to your location (DirecTV Now, Sling TV, NHL and others use location to determine your eligibility for viewing certain programs, particularly live sports and local over-the-air channels). I can even set my Nest thermostat app to use location to determine when to put my heating/cooling system into "away from home" (energy saving) mode.