Recently I've noticed some strange behavior from the GPS on my iPhone 6. If I'm using it to navigate it'll often drift a block to a 1/4 mile of my course and will start recalculating. It happens in both Apple Maps and Google Maps. I've notice the same thing when I use the Endomondo running app. It used to be very accurate, but now I notice it saying I'm passing 1/2 mile check points really early and my pace is way off. When I look at the map at the end of the the run, it has plot points that jump a block or more off my route. It's become somewhat useless for running because the distances don't match what I'm running. When I'm running the Apple Maps I get the 'locating' display at the bottom more than half the time I'm on my route. I've tried a hard reset, but it's still not working. I wanted to check here to see if anybody has experience something similar before I make an appointment to take to get it checked.